crypto/ocsp: add support for Ed25519 signatures in OCSP responses

[Minipada]

This PR is necessary to work with the ocsp server in cfssl. See additional PR there https://github.com/cloudflare/cfssl/pull/1420

This PR adds support for the EdDSA Ed25519 signature algorithm to the OCSP response signing logic. This allows cfssl to generate OCSP responses using Ed25519 keys, in compliance with RFC 8410.

Key Changes:

• added OID for Ed25519 (1.3.101.112) in oidSignatureEd25519
• updated signingParamsForPublicKey to recognize ed25519.PublicKey, set appropriate pkix.AlgorithmIdentifier, and avoid setting Parameters (as required by RFC 8410)
• extended signatureAlgorithmDetails to include x509.PureEd25519
• updated CreateResponse to avoid hashing the TBSResponseData when crypto.Hash(0) is used (i.e., for Ed25519), passing the raw DER directly to priv.Sign
• error messages updated to reflect Ed25519 as a supported key type

Motivation:

Ed25519 is widely adopted due to its performance, small key size, and resistance to common cryptographic attacks. Supporting it in OCSP flows is critical for enabling modern PKI infrastructures that prefer or require Ed25519-based certificates and responders.

Compatibility

This change is backward-compatible. The existing RSA and ECDSA flows remain untouched. Ed25519 is only engaged if the responder key is of type ed25519.PublicKey and the SignatureAlgorithm is x509.PureEd25519.

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Patch Set 1:

(1 comment)

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Patch Set 1:

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Patch Set 5:

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