This Certification Practice Statement ("CPS") document outlines the certification services practices for Internet Security Research Group ("ISRG") Public Key Infrastructure ("ISRG PKI").
ISRG PKI services include, but are not limited to, issuing, managing, validating, revoking, and renewing Certificates in accordance with the requirements of the ISRG Certificate Policy (CP). It is recommended that readers familiarize themselves with the ISRG CP prior to reading this document.
ISRG PKI services are most commonly, but not necessarily exclusively, provided under the brand/trademark "Let's Encrypt".
The ISRG PKI conforms to the current version of the guidelines adopted by the Certification Authority/Browser Forum (“CAB Forum”) when issuing publicly trusted certificates, including the Baseline Requirements for the Issuance and Management of Publicly Trusted Certificates (“Baseline Requirements”). CAB Forum documents can be found at https://www.cabforum.org. If there is any conflict between this CPS and a relevant CAB Forum requirement or guideline, then the CAB Forum requirement or guideline shall take precedence.
Other documents related to the behavior and control of the ISRG PKI, such as a Subscriber Agreement and Privacy Policy, can be found at https://letsencrypt.org/repository/.
Per IETF PKIX RFC 3647, this CPS is divided into nine components that cover security controls, practices, and procedures for certification services provided by the ISRG PKI.
The following Certification Authorities are covered under this CPS:
| CA Type | Distinguished Name | Key Pair Type and Parameters | SHA-256 Key Fingerprint | Validity Period |
|---|---|---|---|---|
| Root CA | C=US, O=Internet Security Research Group, CN=ISRG Root X1 |
RSA, n has 4096 bits, e=65537 | 96:BC:EC:06:26:49:76:F3: 74:60:77:9A:CF:28:C5:A7: CF:E8:A3:C0:AA:E1:1A:8F: FC:EE:05:C0:BD:DF:08:C6 |
Not Before: Jun 4 11:04:38 2015 GMT, Not After: Jun 4 11:04:38 2035 GMT |
This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.
This is the ISRG Certification Practices Statement. This document was approved for publication by the ISRG Policy Management Authority, and is made available at https://letsencrypt.org/repository/.
The following revisions have been made:
| Date | Changes | Version |
|---|---|---|
| May 5, 2015 | Original. | 1.0 |
| September 9, 2015 | Added/corrected a number of policy URIs, removed LDAP as mechanism for publishing certificate information, removed administrative contact requirement for DV-SSL subscribers, removed mention of web-based revocation option, removed description of customer service center, substantial changes to all of Section 9 regarding legal matters, other minor fixes/improvements. | 1.1 |
| September 22, 2015 | Updated serial number description in Section 10.3.1, DV-SSL Certificate Profiles. | 1.2 |
| March 16, 2016 | Update root CRL issuance periods, disallow issuance to ‘.mil’ TLD, make NameConstraints extension optional for cross- certification profile, clarify optional NameConstraints contents, clarify that OSCP ResponderID is byname, clarify that OCSP nonce extension is not supported. | 1.3 |
| May 5, 2016 | Reference CP v1.2 rather than CP v1.1. Add info about tlsFeature extension, serialNumber in Subject Distinguished Name field. | 1.4 |
| October 18, 2016 | Do not require discontinuing use of a private key due to incorrect information in a certificate. Add information about issuance for Internationalized Domain Names. Add information about CA’s CAA identifying domain. Do not require discontinuing use of a private key due to expiration or revocation of a certificate. | 1.5 |
| April 13, 2017 | Complete rewrite of CPS. | 2.0 |
| February 6, 2018 | Remove restriction on issuing to '.mil' TLD. | 2.1 |
| March 10, 2018 | Remove text stating that wildcard certificates are not supported. Clarify that wildcard validation must use DNS Change method. | 2.2 |
| May 4, 2018 | Add CT fields to certificate profiles. Specify current Baseline Requirements compliance for all validations. Update certificate expiration notice text. Remove reference loops. Minor cleanup. | 2.3 |
ISRG is a CA that provides services including, but not limited to, issuing, managing, validating, revoking, and renewing publicly-trusted Certificates. These services are performed in accordance with the requirements of the ISRG Certificate Policy (CP) and this CPS. These services are provided to the general public with exceptions as deemed appropriate by ISRG management or in accordance with relevant law.
ISRG PKI services are most commonly, but not necessarily exclusively, provided under the brand/trademark "Let's Encrypt".
ISRG serves as its own RA. RA services are not performed by third parties.
See definition of "Subscriber" in Section 1.6.1 Definitions.
See definition of "Relying Party" in Section 1.6.1 Definitions.
Relying Parties must verify the validity of certificates via CRL or OCSP prior to relying on certificates. CRL and OCSP location information is provided within certificates.
Other participants include CAs that cross-sign or issue subordinates to the ISRG PKI.
ISRG PKI vendors and service providers with access to confidential information or privileged systems are required to operate in compliance with the ISRG CP.
Certificates issued by ISRG PKI can be used only to establish secure online communication between hosts (as identified by the FQDN provided in the Certificate) and clients using the TLS protocol.
Certificates may not be used:
Also, note that Certificates do not guarantee anything regarding reputation, honesty, or the current state of endpoint security. A Certificate only represents that the information contained in it was verified as reasonably correct when the Certificate was issued.
This CPS document is maintained by the ISRG PMA.
The ISRG PMA can be contacted at:
Policy Management Authority
Internet Security Research Group
1 Letterman Drive, Suite D4700
San Francisco, CA 94129
The ISRG PMA is responsible for determining the suitability of this CPS. The ISRG PMA is informed by results and recommendations received from an independent auditor.
The ISRG PMA approves any revisions to this CPS document after formal review.
ISRG CP, CPS, Privacy Policy, Subscriber Agreement, and WebTrust audit documents are made publicly available in the Policy and Legal Repository, which can be found at:
https://letsencrypt.org/repository/
Records of all ISRG root and intermediate certificates, including those that have been revoked, are available in the Certificate Repository:
https://letsencrypt.org/certificates/
ISRG certificates contain URLs to locations where certificate-related information is published, including revocation information via OCSP and/or CRLs.
New or updated ISRG CP, CPS, Privacy Policy, Subscriber Agreement, and WebTrust audit documents are made publicly available as soon as possible. This typically means within seven days of receipt or approval.
New or updated ISRG root and intermediate certificates are made publicly available as soon as possible. This typically means within seven days of creation.
Read only access to the Policy and Legal Repository and certificate information is unrestricted. Write access is protected by logical and physical controls.
Certificate distinguished names and subject alternative names are compliant with the CP.
ISRG certificates include a "Subject" field which identifies the subject entity (i.e. organization or domain). The subject entity is identified using a distinguished name.
ISRG certificates include an "Issuer" field which identifies the issuing entity. The issuing entity is identified using a distinguished name.
Subscribers are not identified in DV certificates, which have subject fields identifying only domain names (not people or organizations). Relying parties should consider DV certificate subscribers to be anonymous.
Distinguished names in certificates are to be interpreted using X.500 standards and ASN.1 syntax. RFC 2253 and RFC 2616 provide more information.
Certificates do not assert any specific relationship between subscribers and registrants of domain names contained in certificates.
Regarding Internationalized Domain Names, ISRG will have no objection so long as the domain is resolvable via DNS. It is the CA’s position that homoglyph spoofing should be dealt with by registrars, and Web browsers should have sensible policies for when to display the punycode versions of names.
No stipulation.
ISRG reserves the right to make all decisions regarding Subscriber names in certificates. Entities requesting certificates will be required to demonstrate their right to use names (e.g. demonstrate control of a domain name), but trademark rights are not verified.
While ISRG will comply with U.S. law and associated legal orders, it is ISRG's position that trademark enforcement responsibility for domain names should lie primarily with domain registrars and the legal system.
ISRG may elect not to issue any certificate at its sole discretion.
Applicants are required to prove possession of the Private Key corresponding to the Public Key in a Certificate request, which can be done by signing the request with the Private Key.
ISRG only issues Domain Validation (DV) certificates. When a certificate request includes a list of FQDNs in a SAN list, all domains in the list are fully validated prior to issuance.
Validation for DV certificates involves demonstrating proper control over a domain. ISRG validates domain control primarily in an automated fashion via the ACME protocol. In exceptional cases control may be validated using methods similar to those employed by ACME, but performed manually.
There are three methods used for demonstrating domain control:
Agreed-Upon Change to Website: Confirming the Applicant’s control over the requested FQDN by confirming the presence of agreed-upon content contained in a file or on a web page under the “/.well-known/acme-challenge/” directory on the requested FQDN that is accessible to the CA via HTTP over port 80, following redirects. (BR Section 3.2.2.4.6)
DNS Change: Confirming the Applicant’s control over the requested FQDN by confirming the presence of a random value (with at least 128 bits entropy) in a DNS TXT or CAA record for the requested FQDN prefixed with the label '_acme-challenge'. (BR Section 3.2.2.4.7)
TLS Using a Random Number: Confirming the Applicant’s control over the requested FQDN by confirming the presence of a random value (with at least 128 bits entropy) within a Certificate on the requested FQDN which is accessible to the CA via TLS over port 443. (BR Section 3.2.2.4.10)
Validation for wildcard domain requests must be completed using the DNS Change method.
All validations are performed in compliance with the current CAB Forum Baseline Requirements at the time of validation.
ISRG does not issue certificates to individuals, and thus does not authenticate individual identities.
Non-verified Applicant information is not included in ISRG certificates.
ISRG does not issue certificates to organizations, and thus does not validate any natural person's authority to request certificates on behalf of organizations.
Organizations have the option to specify CA issuance authority via CAA records, which ISRG respects.
ISRG discloses Cross Certificates in its Certificate Repository:
https://letsencrypt.org/certificates/
See Section 4.7.
Identification and authentication for revocation requests is performed by ISRG in compliance with Section 4.9 of this document.
Identification and authentication is not required when revocation is being requested by ISRG.
Anyone may submit an application for a certificate via the ACME protocol. Issuance will depend on proper validation and compliance with ISRG policies.
The enrollment process involves the following steps, in no particular order:
ISRG performs all identification and authentication functions in accordance with the ISRG CP. This includes validation per CPS Section 3.2.2.
ISRG checks for relevant CAA records prior to issuing certificates. The CA acts in accordance with CAA records if present. The CA’s CAA identifying domain is ‘letsencrypt.org’.
Approval requires successful completion of validation per Section 3.2.2 as well as compliance with all CA policies.
Certificates containing a new gTLD under consideration by ICANN will not be issued. The CA Server will periodically be updated with the latest version of the Public Suffix List and will consult the ICANN domains section for every requested DNS identifier. CA server will not validate or issue for DNS identifiers that do not have a Public Suffix in the ICANN domains section. The Public Suffix List is updated when new gTLDs are added, and never includes new gTLDs before they are resolvable.
ISRG maintains a list of high-risk domains and blocks issuance of certificates for those domains. Requests for removal from the high-risk domains list will be considered, but will likely require further documentation confirming control of the domain from the Applicant, or other proof as deemed necessary by ISRG management.
No stipulation.
Certificates issued by the Root CA require an individual authorized by ISRG to deliberately issue a direct command in order for the Root CA to perform a certificate signing operation.
The source of a certificate request is confirmed before issuance. CA processes are protected from unauthorized modification during certificate issuance. Issued certificates are stored in a database and then made available to the Subscriber.
End-entity certificates are made available to Subscribers via the ACME protocol as soon after issuance as reasonably possible. Typically this happens within a few seconds.
All end-entity certificates are logged to Certificate Transparency servers as soon as reasonably possible. Typically this happens within a few seconds.
See ISRG CP Section 4.4.1.
All root and intermediate certificates are made available publicly via the Certificate Repository.
All end-entity certificates are made available to Subscribers via the ACME protocol.
All end-entity certificates are logged to Certificate Transparency servers.
See Section 4.4.2.
Subscribers are obligated to generate Key Pairs using reasonably trustworthy systems.
Subscribers are obligated to take reasonable measures to protect their Private Keys from unauthorized use or disclosure (which constitutes compromise). Subscribers must discontinue use of any Private Keys that are known or suspected to have been compromised.
Certificates must be used in accordance with their intended purpose, which is outlined in this CPS and the associated CP. Subscribers must cease use of certificates being used outside of their intended purpose.
Relying Parties must fully evaluate the context in which they are relying on certificates and the information contained in them, and decide to what extent the risk of reliance is acceptable. If the risk of relying on a certificate is determined to be unacceptable, then Relying Parties should not use the certificate or should obtain additional assurances before using the certificate.
ISRG does not warrant that any software used by Relying Parties to evaluate or otherwise handle certificates does so properly.
Relying Parties ignoring certificate expiration, revocation data provided via OCSP or CRL, or other pertinent information do so at their own risk.
Certificate renewal requests are treated as applications for new certificates.
Certificate re-key requests are treated as applications for new certificates.
Certificate modification requests are treated as applications for new certificates.
Certificate revocation permanently ends the certificate's operational period prior to its stated validity period.
ISRG will follow the ISRG CP and revoke a certificate in accordance with Section 4.9.1.1 and Section 4.9.1.2 of the ISRG CP.
ISRG maintains a continuous (24x7x365) ability to accept and respond to revocation requests and related inquiries.
Anyone can revoke any certificate via the ACME API if they can sign the revocation request with the private key associated with the certificate. No other information is required in such cases. A number of ACME clients support this functionality.
Anyone can revoke any certificate via the ACME API if they can demonstrate control over all domains covered by the certificate. No other information is required in such cases. A number of ACME clients support this functionality.
Subscribers can revoke certificates belonging to their accounts via the ACME API if they can sign the revocation request with the associated account private key. No other information is required in such cases. A number of ACME clients support this.
Certificates may be administratively revoked by ISRG if it is determined that the Subscriber has failed to meet obligations under the CP, this CPS, the relevant Subscriber Agreement, or any other applicable agreement, regulation, or law. Certificates may also be administratively revoked at the discretion of ISRG management.
Revocation requests may be made at any time via the ACME API.
All other requests for revocation must be made by emailing cert-prob-reports@letsencrypt.org. ISRG will respond to such requests within 24 hours, though an investigation into the legitimacy of the request may take longer.
An investigation into whether revocation or other appropriate action is warranted will be based on at least the following criteria:
There is no grace period for a revocation request. A revocation request must be made as soon as circumstances requiring revocation are confirmed.
Investigation into a revocation request will begin within 24 hours of receiving the request.
Once a decision has been made to revoke a certificate, revocation will be carried out within 24 hours.
Relying Parties who cannot or choose not to check revocation status, but decide to rely on a certificate anyway, do so at their own risk.
See Section 4.5.2.
ISRG will issue updated CRLs for intermediate certificates with a frequency greater than or equal to that required by the ISRG CP.
ISRG does not issue CRLs for end-entity certificates.
When a CRL is requested by a Relying Party the time to receive a response will be less than ten seconds under normal operating conditions.
Revocation information for all certificates is made available via OCSP. OCSP responses are available at all times (24x7x365) if possible.
See Section 4.9.6.
ISRG allows for OCSP stapling.
No stipulation.
ISRG does not suspend certificates.
Not applicable.
Not applicable.
Not applicable.
CRL entries for intermediate certificates will remain in place until the certificates expire. ISRG does not provide CRLs for end-entity certificates.
OCSP responses will be made available for all unexpired certificates.
All certificate status services are made available at all times (24x7x365) if possible.
No stipulation.
A Subscriber's subscription ends once all of Subscriber's ISRG certificates have expired or been revoked.
Prior to expiration of a Subscriber's certificate, ISRG may send Subscriber a notice regarding upcoming Certificate expiration if a contact email address was provided.
Not applicable.
Not applicable.
ISRG Secure PKI Facilities are located in the United States, as are all copies of CA root and intermediate private keys.
ISRG maintains at least two Secure PKI Facilities at all times for the sake of redundancy.
Secure PKI Facilities are constructed so as to prevent unauthorized entry or interference.
Secure PKI Facilities are monitored at all times (24x7x365) so as to prevent unauthorized entry or interference.
Physical access to ISRG Secure PKI Facilities is restricted to authorized ISRG employees, vendors, and contractors, for whom access is required in order to execute their jobs. Access restrictions are strongly enforced via multi-factor authentication mechanisms.
Redundant power sources are readily available at each Secure PKI Facility, and are designed to meet ISRG's operating requirements.
Air conditioning systems at each Secure PKI Facility are designed to meet ISRG's operating requirements.
ISRG Secure PKI Facilities are designed to protect ISRG infrastructure from water exposure/damage.
ISRG Secure PKI Facilities are designed to prevent fire and provide suppression if necessary.
ISRG Secure PKI Facilities are designed to prevent accidental damage or unauthorized access to media.
ISRG prohibits any media that contains or has contained sensitive data from leaving organizational control in such a state that it may still be operational, or contain recoverable data. Such media may include printed documents or digital storage devices. When media that has contained sensitive information reaches its end of life, the media is physically destroyed such that recovery is reasonably believed to be impossible.
ISRG maintains multiple backups of private keys at multiple Secure PKI Facilities. All backups are stored on devices meeting FIPS 140 Level 3 criteria.
All persons, employees or otherwise, with the ability to materially impact the operation of ISRG PKI systems and services, or the ability to view CA confidential information, must do so while designated as serving in a Trusted Role.
Trusted Roles include, but are not limited to:
Each Trusted Role requires an appropriate level of training and legal obligation.
A number of tasks, such as key generation and entering areas physically containing operating ISRG PKI systems, require at least two people in Trusted Roles to be present.
Anyone performing work in a Trusted Role must identify and authenticate themselves before accessing ISRG PKI systems or confidential information.
Nobody with the ability to deploy software to ISRG PKI systems (e.g. Systems Administrators) may have the ability to commit code to core CA software. The reverse is also true.
ISRG management is responsible for making sure that Trusted Contributors are trustworthy and competent, which includes having proper qualifications and experience.
ISRG management ensures this with appropriate interviewing practices, training, background checks, and regular monitoring and review of Trusted Contributor job performance.
Trusted Contributors must undergo a background check prior to performing in a trusted role. ISRG management will review the results of background checks for problematic issues prior to approving performance of a trusted role.
Background checks include, but are not limited to, criminal background and employment history.
Trusted Contributors must be trained on topics relevant to the role in which they will perform.
Training programs are developed for each role by ISRG management and Security Officers.
Training is repeated for each Trusted Contributor on an annual basis and re-covers all topics relevant to their trusted role.
Training is also offered whenever changes in the industry or operations require it in order for contributors to competently perform in their trusted roles.
No stipulation.
Action will be taken to safeguard ISRG and its subscribers whenever ISRG Trusted Contributors, whether through negligence or malicious intent, fail to comply with ISRG policies including this CPS.
Actions taken in response to non-compliance may include termination, removal from trusted roles, or reporting to legal authorities.
Once management becomes aware of non-compliance the Trusted Contributor(s) in question will be removed from trusted roles until a review of their actions is complete.
Independent contractors who are assigned to perform Trusted Roles are subject to the duties and requirements specified for such roles in this CPS and the accompanying CP. This includes those described in Section 5.3. Potential sanctions for unauthorized activities by independent contractors are described in Section 5.3.6.
Trusted Contributors are provided with all documentation necessary to perform their duties. This always includes, at a minimum, a copy of the ISRG CP, CPS, and Information Security Policy.
Audit logs are generated for all events related to CA security (physical and logical) and certificate issuance. Logs are automatically generated whenever possible. When it is necessary to manually log information, logs are kept on paper with written confirmation from a witness and securely stored. All audit logs, electronic or otherwise, shall be retained and made available to compliance auditors upon request.
At a minimum, each audit record includes:
No stipulation.
Audit logs are retained for at least seven years and will be made available to compliance auditors upon request.
Audit logs, whether in production or archived, are protected using both physical and logical access controls.
ISRG makes regular backup copies of audit logs. Audit log backup copies are sent for secure offsite storage at least once per month.
Audit data is automatically generated and reported/recorded by operating systems, CA software applications, and network devices. Systems are in place to ensure proper reporting and recording of audit data, and the failure of such systems may lead to suspension of CA services until proper audit log reporting is restored.
No stipulation.
Audit logs are monitored by Trusted Contributors, including operations and engineering staff. Anomalies indicating attempted breaches of CA security are reported and investigated.
Automated internal and external vulnerability scans occur at least every two weeks, though more typically every week.
Extensive vulnerability assessments for ISRG infrastructure and primary CA application code are conducted at least annually by qualified third parties.
ISRG Security Officers perform a risk assessment at least annually. This risk assessment:
Identifies foreseeable internal and external threats that could result in unauthorized access, disclosure, misuse, alteration, or destruction of any Certificate Data or Certificate Management Processes;
Assesses the likelihood and potential damage of these threats, taking into consideration the sensitivity of the Certificate Data and Certificate Management Processes; and
Assesses the sufficiency of the policies, procedures, information systems, technology, and other arrangements that the CA has in place to counter such threats.
ISRG archives all audit logs, the contents of which are described in Section 5.4.1. ISRG may also archive any other information deemed critical to understanding the historical performance of the CA's duties.
ISRG retains all documentation relating to certificate requests and the verification thereof, and all Certificates and revocation thereof, for at least seven years after any Certificate based on that documentation ceases to be valid.
Archives are protected from unauthorized modification or destruction by strong security and environmental controls at primary and offsite storage facilities.
Archives are backed up at primary CA facilities as well as at secure off-site facilities.
Records are time-stamped as they are created.
Machine-created records use system time, which is synchronized automatically with third-party time sources. Machines without network access have the time set manually.
Manual records use a manually entered date and time, complete with time zone in use.
No stipulation.
No stipulation.
When a CA certificate is nearing expiration, a key changeover procedure is used to transition to a new CA certificate. The following steps constitute a key changeover procedure:
Some time prior to CA certificate expiration, the private key associated with the expiring certificate is no longer used to sign new certificates. It is only used to sign CRLs and OCSP responses.
A new key pair is generated and a new CA certificate is created containing the new key pair's public key. This new key pair is used to sign new certificates.
If necessary or desired, the old private key associated with the expiring certificate may be used to cross-sign the new certificate.
ISRG has created and maintains incident response procedures for a range of potential compromise and disaster situations. Such situations include, but are not limited to, natural disasters, security incidents, and equipment failure. Incident response plans are reviewed, potentially updated, and tested on at least an annual basis.
In the event that computing resources, software, and/or data are corrupted or otherwise damaged, ISRG will assess the situation, including its impact on CA integrity and security, and take appropriate action. CA operations may be suspended until mitigation is complete. Subscribers may be notified if corruption or damage has a material impact on the service provided to them.
In the event that a CA Private Key is compromised, or suspected to be compromised, ISRG will immediately launch a thorough investigation. Forensic evidence will be collected and secured as quickly as possible. If it cannot be determined with a high degree of certainty that the private key in question was not compromised, then the following steps may be taken in whatever order is deemed most appropriate by ISRG Security Officers:
ISRG maintains multiple geographically diverse facilities, each of which is capable of operating ISRG CA systems independently. In the event that a disaster entirely disables one facility, ISRG CA operations will fail over to another facility.
In the event that ISRG CA services are to be terminated:
If a suitable successor entity exists, the following steps will be taken:
If a suitable successor entity does not exist, the following steps will be taken:
CA private keys are generated by HSMs meeting the requirements of Section 6.2.1. This occurs during a ceremony meeting the requirements of this CPS and the accompanying CP.
Subscriber key pairs are generated and managed by Subscribers. Generation and management of Subscriber key pairs must be done in compliance with the terms of the CA Subscriber Agreement and ISRG CPS Section 9.6.3.
ISRG never generates or has access to Subscriber Private Keys.
Subscriber Public Keys are communicated to ISRG electronically via the ACME protocol.
ISRG Public Keys are provided to Relying Parties as part of browser, operating system, or other software trusted root certificate lists.
ISRG Public Keys are also available on ISRG websites such as letsencrypt.org.
ISRG CA root Private Keys are RSA keys at least 4096 bits in length.
ISRG CA intermediate Private Keys are RSA keys at least 2048 bits in length.
ISRG uses HSMs conforming to FIPS 186-4, capable of providing random number generation and on-board creation of at least 2048-bit RSA keys.
Per Section 5.3.3, NIST SP 800‐89, the CA ensures that the public exponent of the RSA Keys for a DV-SSL Certificates is in the range between 216+1 and 2256-1. The moduli are an odd number, not the power of a prime, and have no factors smaller than 752.
See Section 7, Certificate Profiles.
ISRG uses HSMs meeting FIPS 140-2 Level 3 (or higher) requirements.
ISRG has put into place security mechanisms which require multiple people performing in Trusted Roles in order to access CA Private Keys, both physically and logically. This is true for all copies of Private Keys, in production or backups, on-site or off-site.
ISRG does not escrow CA Private Keys and does not provide such a service for Subscribers.
Critical ISRG Private Keys are backed up both on-site and off-site, in multiple geographic locations, under multi-person control.
ISRG does not archive private keys.
ISRG CA Private Keys are generated inside HSMs and are only transferred between HSMs for redundancy or backup purposes. When transferred, keys are encrypted prior to leaving HSMs and unwrapped only inside destination HSMs. Keys never exist in plain text form outside of HSMs.
ISRG CA Private Keys are stored on HSMs meeting the requirements stated in Section 6.2.1.
ISRG CA Private Keys are always stored on HSMs and activated using the mechanisms provided by the HSM manufacturer. Activation data and devices are protected.
ISRG CA Private Keys are always stored on HSMs and deactivated using the mechanisms provided by the HSM manufacturer.
ISRG CA Private Keys are destroyed by Trusted Contributors using a FIPS 140-2 (or higher) validated zeroize method provided by the HSMs storing the keys. Physical destruction of the HSM is not required.
Subscribers are obligated to securely destroy private keys when they should no longer be used, in most cases by securely deleting all copies of private key files from storage media.
See Section 6.2.1.
See Section 5.5.
The lifetimes of ISRG Root CA certificates are specified in Section 1.1. Corresponding key pairs have the same lifetimes.
End-entity certificates issued by ISRG to Subscribers shall have a validity period less than 100 days. Subscriber key pairs may be re-used indefinitely provided that there is no suspicion or confirmation of Private Key compromise.
Activation data used to activate CA Private Keys is generated during a key ceremony. Activation data is transferred to the person who will use it, or place it will be stored, in a secure fashion.
Activation data is protected from unauthorized disclosure via a combination of physical and logical means.
No stipulation.
ISRG CA infrastructure and systems are appropriately secured in order to protect CA software and data from unauthorized access or modification. Access to systems is secured via multi-factor authentication whenever possible. Security updates are applied in a timely fashion. Vulnerability scans are run regularly.
No stipulation.
ISRG has developed policies and procedures to effectively manage the acquisition and development of its CA systems.
ISRG CA hardware and software is dedicated solely to performing CA functions.
Vendor selection includes an evaluation of reputation in the market, ability to deliver a quality product, vulnerability history, and the likelihood of remaining viable in the future. Purchases are made in such a way that as little information about the future use of products as possible is disclosed. Physical product deliveries are received by Trusted Contributors and inspected for evidence of tampering. HSMs are shipped in tamper-evident packaging and tamper bag serial numbers are confirmed with the vendor upon reception.
ISRG maintains a CA testing environment separate from the production environment. The testing environment matches the production environment as closely as reasonably possible but does not have access to CA Private Keys used in trusted certificates. The purpose of this testing platform is to allow extensive but safe testing of software and systems that are or will be deployed to the CA production environment.
ISRG has developed and maintains appropriate change control policies and procedures to be followed any time CA systems are modified. Changes to ISRG CA systems require review by qualified Trusted Personnel who are different from the person requesting the change. Change requests are documented, as are any subsequent required reviews or approvals.
When ISRG develops software to be used in CA operations, software development policies are put into place and methodologies are followed in order to ensure software quality and integrity. This always includes a requirement for peer review of code changes. Unit testing is strongly encouraged. Code commit privileges are granted only to qualified and trusted contributors. Nobody with the ability to deploy software to ISRG PKI systems (e.g. Systems Administrators) may have the ability to commit code to core CA software. The reverse is also true.
ISRG has mechanisms in place to control and monitor security-related configuration of CA systems. Equipment and software is installed and configured using a documented change control process. Software integrity is verified upon deployment using checksums.
No stipulation.
ISRG implements reasonable network security safeguards and controls to prevent unauthorized access to CA systems and infrastructure. ISRG's network is multi-tiered and utilizes the principle of defense in depth.
Firewalls and other critical CA systems are configured based on a necessary-traffic-only whitelisting policy whenever possible.
ISRG root CA Private Keys are stored offline in a secure manner.
See Section 5.5.5.
All fields are as specified in RFC5280, including fields and extensions not specifically mentioned. Extensions are not marked critical unless specifically described here as critical.
| Field or extension | Value |
|---|---|
| Serial Number | Must be unique, with 64 bits of output from a CSPRNG |
| Issuer Distinguished Name | C=US, O=Internet Security Research Group, CN=ISRG Root X<n> where n is an integer representing the instance of the Root CA Certificate. For example, ISRG Root X1, ISRG Root X2, etc. |
| Subject Distinguished Name | Same as Issuer DN |
| Validity Period | Up to 25 years |
| Basic Constraints | Critical. cA=True, pathLength constraint absent |
| Key Usage | Critical. keyCertSign, cRLSign |
| Field or extension | Value |
|---|---|
| Serial Number | Must be unique, with 64 bits of output from a CSPRNG |
| Issuer Distinguished Name | Derived from Issuer certificate |
| Subject Distinguished Name | C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X<n> where n is an integer representing the instance of the Subordinate CA Certificate |
| Validity Period | Up to 8 years |
| Basic Constraints | Critical. cA=True, pathLength constraint 0 |
| Key Usage | Critical. keyCertSign, cRLSign, digitalSignature |
| Extended Key Usage | TLS Server Authentication, TLS Client Authentication |
| Certificate Policies | CAB Forum Domain Validated (2.23.140.1.2.1) ISRG Domain Validated (1.3.6.1.4.1.44947.1.1.1) Policy Qualifier Id=CPS Qualifier: Pointer to this CPS |
| Authority Information Access | Contains CA Issuers URL and OCSP URL. URLs vary based on Issuer. |
| CRL Distribution Points | Contains a CRL URL. URL varies based on Issuer. |
| Field or extension | Value |
|---|---|
| Serial Number | Must be unique, with 64 bits of output from a CSPRNG |
| Issuer Distinguished Name | Derived from Issuer certificate |
| Subject Distinguished Name | CN=one of the values from the Subject Alternative Name extension |
| Validity Period | 90 days |
| Basic Constraints | Critical. cA=False |
| Key Usage | Critical. digitalSignature, keyEncipherment |
| Extended Key Usage | TLS Server Authentication, TLS Client Authentication |
| Certificate Policies | CAB Forum Domain Validated (2.23.140.1.2.1) ISRG Domain Validated (1.3.6.1.4.1.44947.1.1.1) CPS Qualifier: Pointer to this CPS User Notice Qualifier: Message to potential relying parties |
| Authority Information Access | Contains CA Issuers URL and OCSP URL. URLs vary based on Issuer. |
| Subject Public Key | RSA with modulus between 2048 and 4096, inclusive; or namedCurve P-256; or namedCurve P-384 |
| Subject Alternative Name | A sequence of 1 to 100 dNSNames |
| TLS Feature | Contains status_request if requested by the subscriber in the CSR |
| Precertificate poison | Per RFC 6962. In Precertificates only. |
| Signed Certificate Timestamp List | Per RFC 6962. In final certificates only. |
Signed by a Root CA Certificate, these Certificates sign OCSP responses for Intermediate CA Certificates.
| Field or extension | Value |
|---|---|
| Serial Number | Must be unique, with 64 bits of output from a CSPRNG |
| Issuer Distinguished Name | C=US, O=Internet Security Research Group, CN=ISRG Root X<n> |
| Subject Distinguished Name | C=US, O=Internet Security Research Group, CN=ISRG Root OCSP X<n> |
| Validity Period | 5 years |
| Basic Constraints | Critical. cA=False |
| Key Usage | Critical. digitalSignature |
| Extended Key Usage | Critical. OCSPSigning |
| No Check | Present |
All certificates use X.509 version 3.
See section 7.1.
| Name | Object identifier |
|---|---|
| sha256WithRSAEncryption | 1.2.840.113549.1.1.11 |
See ISRG Certificate Policy.
ISRG will not issue Certificates for IP addresses.
These restrictions are not enforced by a NameConstraints extension.
See section 7.1.
Not applicable.
See section 7.1.
Not applicable.
| Field or Extension | Value |
|---|---|
| Version | V2 |
| Signature Algorithm | sha256WithRSAEncryption |
| ThisUpdate | The date and time when the Certificate revocation list was issued. |
| NextUpdate | ThisUpdate + 30 days |
| RevokedCertificates | Contains: userCertificate, revocationDate, reasonCode |
| CRLnumber | The serial number of this CRL in an incrementally increasing sequence of CRLs. |
See section 7.2.
No stipulation.
ISRG OCSP responders implement the RFC 5019 profile of RFC 6960.
No stipulation.
No stipulation.
WebTrust compliance audits are intended to ensure a CA's compliance with its CP and CPS and relevant WebTrust audit criteria.
WebTrust compliance audit periods cover no more than one year and are scheduled by ISRG annually, every year with no gaps.
See Section 8.7 for information about the frequency of self-audits.
ISRG's WebTrust compliance audits are performed by a qualified auditor. A qualified auditor means a natural person, legal entity, or group of natural persons or legal entities that collectively possess the following qualifications and skills:
ISRG's WebTrust auditors shall have no financial interest in, or other type of relationship with, ISRG, which might cause the auditors to have a bias for or against ISRG.
Compliance audits cover ISRG's compliance with the ISRG CP and this CPS, as well as the following WebTrust principles and criteria:
Noncompliance with relevant requirements will be documented by auditors (internal or external), the ISRG PMA will be informed, and the ISRG PMA will ensure that steps are taken to address the issues as quickly as reasonably possible.
Audit results are reported to the ISRG PMA and any other entity entitled to the results by law, regulation, or agreement. This includes a number of Web user agent (i.e. browser) root programs.
ISRG is not required to publicly disclose any audit finding that does not impact the overall audit opinion.
ISRG performs a quarterly internal audit of at least 3% of issuance since the last WebTrust audit period. The sample is randomly selected. Results are saved and provided to auditors upon request.
ISRG does not charge any fees for certificate issuance or renewal.
No stipulation.
ISRG does not charge any fees for certificate revocation or for checking the validity status of an issued certificate using a CRL or OSCP.
No stipulation.
ISRG collects no fees, and so provides no refunds.
No stipulation.
No stipulation.
No stipulation.
No stipulation.
No stipulation.
ISRG employees, agents, and contractors are responsible for protecting confidential information and are bound by ISRG’s policies with respect to the treatment of confidential information or are contractually obligated to do so. Employees receive training on how to handle confidential information.
ISRG follows the privacy policy posted on its website (https://letsencrypt.org/repository/) when handling personal information.
The privacy policy posted on ISRG’s website (https://letsencrypt.org/repository/) identifies information that ISRG treats as private.
The privacy policy posted on ISRG’s website (https://letsencrypt.org/repository/) identifies information that ISRG does not treat as private.
ISRG employees and contractors are subject to policies or contractual obligations requiring them to comply with ISRG’s privacy policy (https://letsencrypt.org/repository/) or contractual obligations at least as protective of private information as ISRG’s privacy policy.
ISRG follows the privacy policy posted on its website (https://letsencrypt.org/repository/) when using personal information.
ISRG may disclose personal information if compelled to do so by court order or other compulsory legal process, provided that ISRG will oppose such disclosure with all legal and technical tools reasonably available to ISRG.
ISRG may disclose personal information under other circumstances that are described in the privacy policy posted on its website (https://letsencrypt.org/repository/).
ISRG and/or its business partners own the intellectual property rights in ISRG’s services, including the certificates, trademarks used in providing the services, and this CPS. Certificate and revocation information are the property of ISRG. ISRG grants permission to reproduce and distribute certificates on a non-exclusive and royalty-free basis, provided that they are reproduced and distributed in full. Private Keys and Public Keys remain the property of the Subscribers who rightfully hold them.
Notwithstanding the foregoing, third party software (including open source software) used by ISRG to provide its services is licensed, not owned, by ISRG.
Except as expressly stated in this CPS or in a separate agreement with a Subscriber, ISRG does not make any representations or warranties regarding its products or services. ISRG represents and warrants, to the extent specified in this CPS, that:
Each RA represents and warrants that:
ISRG’s agreement with the RA may contain additional representations and warranties.
Each Relying Party represents and warrants that, prior to relying on an ISRG certificate, it:
Any unauthorized reliance on a certificate is at a party’s own risk.
No stipulation.
ISRG CERTIFICATES AND SERVICES ARE PROVIDED “AS-IS.” ISRG DISCLAIMS ANY AND ALL WARRANTIES OF ANY TYPE, WHETHER EXPRESS OR IMPLIED, INCLUDING AND WITHOUT LIMITATION ANY IMPLIED WARRANTY OF TITLE, NON-INFRINGEMENT, MERCHANTABILITY, OR FITNESS FOR A PARTICULAR PURPOSE, IN CONNECTION WITH ANY ISRG SERVICE OR ISRG CERTIFICATE.
ISRG DOES NOT ACCEPT ANY LIABILITY FOR ANY LOSS, HARM, CLAIM, OR ATTORNEY’S FEES IN CONNECTION WITH ANY CERTIFICATES. ISRG WILL NOT BE LIABLE FOR ANY DAMAGES, ATTORNEY’S FEES, OR RECOVERY, REGARDLESS OF WHETHER SUCH DAMAGES ARE DIRECT, CONSEQUENTIAL, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, PUNITIVE, OR COMPENSATORY, EVEN IF ISRG HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. THIS LIMITATION ON LIABILITY APPLIES IRRESPECTIVE OF THE THEORY OF LIABILITY, I.E., WHETHER THE THEORY OF LIABILITY IS BASED UPON CONTRACT, WARRANTY, INDEMNIFICATION, CONTRIBUTION, TORT, EQUITY, STATUTE OR REGULATION, COMMON LAW, OR ANY OTHER SOURCE OF LAW, STANDARD OF CARE, CATEGORY OF CLAIM, NOTION OF FAULT OR RESPONSIBILITY, OR THEORY OF RECOVERY. THIS DISCLAIMER IS INTENDED TO BE CONSTRUED TO THE FULLEST EXTENT ALLOWED BY APPLICABLE LAW.
WITHOUT WAIVING OR LIMITING THE FOREGOING IN ANY WAY, ISRG DOES NOT MAKE, AND ISRG EXPRESSLY DISCLAIMS, ANY WARRANTY REGARDING ITS RIGHT TO USE ANY TECHNOLOGY, INVENTION, TECHNICAL DESIGN, PROCESS, OR BUSINESS METHOD USED IN EITHER ISSUING CERTIFICATES OR PROVIDING ANY OF ISRG’S SERVICES. EACH SUBSCRIBER AFFIRMATIVELY AND EXPRESSLY WAIVES THE RIGHT TO HOLD ISRG RESPONSIBLE IN ANY WAY, OR SEEK INDEMNIFICATION AGAINST ISRG, FOR ANY INFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS, INCLUDING PATENT, TRADEMARK, TRADE SECRET, OR COPYRIGHT.
The CA does not provide any indemnification except as described in Section 9.9.1 of the Certificate Policy.
Each Subscriber will indemnify and hold harmless ISRG and its directors, officers, employees, agents, and affiliates from any and all liabilities, claims, demands, damages, losses, costs, and expenses, including attorneys’ fees, arising out of or related to: (i) any misrepresentation or omission of material fact by Subscriber to ISRG, irrespective of whether such misrepresentation or omission was intentional, (ii) Subscriber’s violation of the Subscriber Agreement, (iii) any compromise or unauthorized use of an ISRG certificate or corresponding Private Key, or (iv) Subscriber’s misuse of an ISRG certificate. If applicable law prohibits Subscriber from providing indemnification for another party’s negligence or acts, such restriction, or any other restriction required by law for this indemnification provision to be enforceable, shall be deemed to be part of this indemnification provision.
To the extent permitted by law, each Relying Party shall indemnify ISRG, its partners, and any cross-signed entities, and their respective directors, officers, employees, agents, and contractors against any loss, damage, or expense, including reasonable attorney’s fees, related to the Relying Party’s (i) breach of any service terms applicable to the services provided by ISRG or its affiliates and used by the Relying Party, this CPS, or applicable law; (ii) unreasonable reliance on a certificate; or (iii) failure to check the certificate’s status prior to use.
This CPS and any amendments to this CPS are effective when published to the ISRG online repository and remain in effect until replaced with a newer version.
This CPS and any amendments remain in effect until replaced with a newer version.
ISRG will communicate the conditions and effect of this CPS’s termination via the ISRG Repository. The communication will specify which provisions survive termination. At a minimum, all responsibilities related to protecting confidential information will survive termination. All Subscriber Agreements remain effective until the certificate is revoked or expired, even if this CPS terminates.
ISRG accepts notices related to this CPS at the locations specified in Section 1.5.2 of this CPS. Notices are deemed effective after the sender receives a valid and digitally signed acknowledgment of receipt from ISRG. If an acknowledgement of receipt is not received within five days, the sender must resend the notice in paper form to the street address specified in Section 1.5.2 of this CPS using either a courier service that confirms delivery or via certified or registered mail with postage prepaid and return receipt requested. ISRG may allow other forms of notice in its Subscriber Agreements.
This CPS is reviewed at least annually and may be reviewed more frequently. Amendments are made by posting an updated version of the CPS to the online repository. Controls are in place that are designed to reasonably ensure that this CPS is not amended and published without the prior authorization of the ISRG PMA.
ISRG posts CPS revisions to its Repository. ISRG does not guarantee or set a notice-and-comment period and may make changes to this CPS without notice.
The ISRG PMA is solely responsible for determining whether an amendment to the CPS requires an OID change.
Any claim, suit or proceeding arising out of this CPS or any ISRG product or service must be brought in a state or federal court located in San Jose, California. ISRG may seek injunctive or other relief in any state, federal, or national court of competent jurisdiction for any actual or alleged infringement of its, its affiliates, or any third party’s intellectual property or other proprietary rights.
The laws of the state of California, United States of America, govern the interpretation, construction, and enforcement of this CPS and all proceedings related to ISRG products and services, including tort claims, without regard to any conflicts of law principles. The United Nations Convention for the International Sale of Goods does not apply to this CPS.
This CPS is subject to all applicable laws and regulations, including United States restrictions on the export of software and cryptography products.
ISRG contractually obligates each RA to comply with this CPS and applicable industry guidelines. ISRG also requires each party using its products and services to enter into an agreement that delineates the terms associated with the product or service. If an agreement has provisions that differ from this CPS, then the agreement with that party controls, but solely with respect to that party. Third parties may not rely on or bring action to enforce such agreement.
Any entities operating under this CPS may not assign their rights or obligations without the prior written consent of ISRG. Unless specified otherwise in a contract with a party, ISRG does not provide notice of assignment.
If any provision of this CPS is held invalid or unenforceable by a competent court or tribunal, the remainder of the CPS will remain valid and enforceable. Each provision of this CPS that provides for a limitation of liability, disclaimer of a warranty, or an exclusion of damages is severable and independent of any other provision.
ISRG may seek indemnification and attorneys’ fees from a party for damages, losses, and expenses related to that party’s conduct. ISRG’s failure to enforce a provision of this CPS does not waive ISRG’s right to enforce the same provision later or right to enforce any other provision of this CPS. To be effective, waivers must be in writing and signed by ISRG.
ISRG is not liable for any delay or failure to perform an obligation under this CPS to the extent that the delay or failure is caused by an occurrence beyond ISRG’s reasonable control. The operation of the Internet is beyond ISRG’s reasonable control.
No stipulation.