Supported Algorithms

SignServer supports the following algorithm types:

Classic
Post-quantum Cryptographic (PQC): Indicated with a pqc label.
Composite: A combination of a classic and a quantum-safe algorithms.

What is post-quantum cryptography?

Post-quantum or quantum-safe cryptography is cryptography that is resistant to the theoretical threat that a cryptographically relevant quantum computer could port. While such a quantum computer does not yet exist, governments and standardization organizations are working towards a migration from classic asymmetric cryptography to new quantum-safe cryptography algorithms. The largest actor in this process is the National Institute of Standards and Technology (NIST).

NIST has announced the standardization of three post-quantum cryptography (PQC) algorithms, FIPS 203 for ML-KEM (derived from CRYSTALS-KYBER), FIPS 204 for ML-DSA (derived from CRYSTALS-Dilithium), and FIPS 205 for SLH-DSA (derived from SPHINCS+).

A fourth digital signature standard FN-DSA (derived from FALCON) will follow. In addition, there are two stateful hash-based signature (SHBS) algorithms standardized in NIST SP800-208 and IETF.

What are composite algorithms?

Composite certificates are advanced digital certificates (X.509) that combine multiple cryptographic keys and signatures, typically a traditional algorithm (like RSA) and a quantum-safe cryptographic algorithm, into a single, secure entity. This dual-algorithm design enables defense in depth during the transition to quantum-safe cryptography, ensuring security remains intact even if one algorithm is compromised.

See SignServer Composite Certificates.

For more information, see the individual algorithm support pages under each Worker or Crypto Token.

Signers also rely on support for the algorithm in the Crypto Token used. Ensure that the desired algorithm is supported by the configured Crypto Token.

Compliant with NSA SUITE B algorithms and certificates. For an external reference of the message digests, see FIPS PUB 180-4.

Supported Algorithms

SignServer supports the following algorithm types and key specifications:

Key Algorithm	Key Specification	Signature Algorithm	Signer Support	Crypto Token Support	HSM Support ^{Supported HSMs}	External Reference
ECDSA	Algorithm with named curves.	SHA1withECDSA	Plain, CMS, MS Authenticode	PKCS#11, Keystore		X9.62, FIPS PUB 186-5, RFC 5639, RFC 6979, SP 800-56A
		SHA224withECDSA	Plain, CMS	P11NG
		SHA256withECDSA	Plain, CMS, OpenPGP, MS Authenticode	Fortanix, Azure Key Vault^*, PKCS#11, P11NG, Keystore
		SHA384withECDSA	Plain, CMS, OpenPGP	Azure Key Vault^*, PKCS#11, P11NG, Keystore
		SHA512withECDSA	Plain, CMS, OpenPGP, MS Authenticode	Fortanix, Azure Key Vault^*, PKCS#11, P11NG, Keystore
		NONEwithECDSA	Plain	Fortanix^, PKCS#11^, P11NG^*, Keystore
EdDSA	Ed25519	Ed25519	Plain, CMS	Fortanix^*, P11NG		RFC 7748, RFC 8032 RFC 8410
EdDSA	Ed448	Ed448	Plain, CMS	P11NG		RFC 7748, RFC 8032 RFC 8410
RSA _{RSASSA-PKCS1_v1.5} _RSASSA-PSS	Keys up to and including 8192 bits.	SHA1withRSA	Plain, CMS, OpenPGP	PKCS#11, P11NG, Keystore		RFC 8017, FIPS PUB 186-5, SP 800-56B
		SHA224withRSA	Plain, CMS, OpenPGP	PKCS#11, P11NG
		SHA256withRSA	Plain, CMS, OpenPGP	Fortanix, Azure Key Vault, PKCS#11, P11NG, Keystore
		SHA384withRSA	Plain, CMS, OpenPGP	Azure Key Vault, PKCS#11, P11NG, Keystore
		SHA512withRSA	Plain, CMS, AdES, OpenPGP	Fortanix, Azure Key Vault, PKCS#11, P11NG, Keystore
		NONEwithRSA	Plain	PKCS#11^, P11NG^, Keystore
		SHA1withRSAandMGF1	Plain, CMS, MRTD SOD	PKCS#11, P11NG, Keystore
		SHA224withRSAandMGF1	Plain, CMS, MRTD SOD	PKCS#11, P11NG
		SHA256withRSAandMGF1	Plain, CMS, AdES, MRTD SOD	Fortanix, PKCS#11, P11NG, Keystore
		SHA384withRSAandMGF1	Plain, CMS, AdES, MRTD SOD	PKCS#11, P11NG, Keystore
		SHA512withRSAandMGF1	CMS, AdES, MRTD SOD	Fortanix, PKCS#11, P11NG, Keystore
		NONEwithRSAandMGF1	Plain	P11NG^*, Keystore
ML-DSA pqc	ML-DSA-44	ML-DSA-44	Plain, CMS^*	PKCS#11, P11NG, Keystore	Entrust nShield Connect/5c Fortanix Data Security Manager (DSM) Thales Luna 7 Utimaco u.trust Anchor	FIPS PUB 204
	ML-DSA-65	ML-DSA-65	Plain, CMS^*	PKCS#11, P11NG, Keystore
	ML-DSA-87	ML-DSA-87	Plain, CMS^*	PKCS#11, P11NG, Keystore
	ML-DSA	ML-DSA-EXTERNAL-MU	Plain, CMS^*	Keystore
SLH-DSA pqc	SLH-DSA	SLH-DSA-SHA2-128F	Plain, CMS^*	Keystore	Fortanix Data Security Manager (DSM)	FIPS PUB 205
	SLH-DSA	SLH-DSA-SHA2-128S	Plain, CMS^*	Keystore
	SLH-DSA	SLH-DSA-SHA2-192F	Plain, CMS^*	Keystore
	SLH-DSA	SLH-DSA-SHA2-192S	Plain, CMS^*	Keystore
	SLH-DSA	SLH-DSA-SHA2-256F	Plain, CMS^*	Keystore
	SLH-DSA	SLH-DSA-SHA2-256S	Plain, CMS^*	Keystore
	SLH-DSA	SLH-DSA-SHAKE-128F	Plain, CMS^*	Keystore
	SLH-DSA	SLH-DSA-SHAKE-128S	Plain, CMS^*	Keystore
	SLH-DSA	SLH-DSA-SHAKE-192F	Plain, CMS^*	Keystore
	SLH-DSA	SLH-DSA-SHAKE-192S	Plain, CMS^*	Keystore
	SLH-DSA	SLH-DSA-SHAKE-256F	Plain, CMS^*	Keystore
	SLH-DSA	SLH-DSA-SHAKE-256S	Plain, CMS^*	Keystore
Composites	ML-DSA-44 & RSA 2048	MLDSA44-RSA2048-PSS-SHA256	Plain	P11NG, Keystore
	ML-DSA-44 & ECDSA	MLDSA44-ECDSA-P256-SHA256	Plain	P11NG, Keystore
	ML-DSA-44 & Ed25519	MLDSA44-Ed25519-SHA512	Plain	P11NG
	ML-DSA-65 & RSA 3072	MLDSA65-RSA3072-PSS-SHA512	Plain	P11NG, Keystore
	ML-DSA-65 & RSA 4096	MLDSA65-RSA4096-PSS-SHA512	Plain	P11NG, Keystore
	ML-DSA-65 & ECDSA	MLDSA65-ECDSA-P256-SHA512	Plain	P11NG, Keystore
	ML-DSA-65 & ECDSA	MLDSA65-ECDSA-P384-SHA512	Plain	P11NG, Keystore
	ML-DSA-65 & ECDSA	MLDSA65-ECDSA-brainpoolP256r1-SHA512	Plain	P11NG, Keystore
	ML-DSA-65 & Ed25519	MLDSA65-Ed25519-SHA512	Plain	P11NG
	ML-DSA-87 & RSA 3072	MLDSA87-RSA3072-PSS-SHA512	Plain	P11NG, Keystore
	ML-DSA-87 & RSA 4096	MLDSA87-RSA4096-PSS-SHA512	Plain	P11NG, Keystore
	ML-DSA-87 & ECDSA	MLDSA87-ECDSA-P384-SHA512	Plain	P11NG, Keystore
	ML-DSA-87 & ECDSA	MLDSA87-ECDSA-P521-SHA512	Plain	P11NG, Keystore
	ML-DSA-87 & ECDSA	MLDSA87-ECDSA-brainpoolP384r1-SHA512	Plain	P11NG, Keystore
	ML-DSA-87 & Ed448	MLDSA87-Ed448-SHAKE256	Plain	P11NG

^*^{Refer to individual algorithm support page for more information.}