SSH Public Key Fingerprint & Converter
Validates a supplied OpenSSH public-key blob and reports its SHA-256 fingerprint and metadata. It does not convert the key to another format.
About this ssh public key fingerprint & converter
Validates a supplied OpenSSH public-key blob and reports its SHA-256 fingerprint and metadata. It does not convert the key to another format Runs entirely in-memory using Web Crypto primitives to keep sensitive tokens, certificates, and cryptographic keys secure from third-party interception.
Encoding & cryptographic principles
Parses, inspects, and validates public key infrastructure certificates and requests conforming to RFC 5280 (X.509 v3 Certificates), RFC 2986 (PKCS#10 Certificate Signing Requests - CSR), and RFC 7468 (PEM Encapsulation). Deconstructs ASN.1 DER binary byte streams to extract Subject, Issuer, Validity Period (NotBefore / NotAfter), Public Key Algorithm (RSA, ECDSA, Ed25519), Key Usage, Extended Key Usage, and Subject Alternative Names (SANs). Calculates SHA-256 certificate fingerprints and validates public key matching.
Worked verification example
Scenario: A developer calculates the SHA-256 fingerprint of an SSH public key before adding it to GitHub.
Sample input:
Processing: Decodes Base64 key body, computes SHA-256 hash, and formats standard OpenSSH fingerprint.
Illustrative output:
Security parameters & input constraints
Only supported OpenSSH public-key shapes are accepted; malformed/trailing blob data is rejected. The fingerprint identifies supplied bytes, not key ownership, server identity, authorized_keys status or trust. Private keys and certificates are not parsed.
Cryptographic digests, encoded strings, and signatures generated by SSH Public Key Fingerprint & Converter should be verified against target authentication systems before production use.
Client-side Web Crypto boundary
Key derivation, hashing, and encoding in SSH Public Key Fingerprint & Converter execute in local memory using Web Crypto APIs without remote socket transmission.
Cryptographic specifications & RFC standards
Technical specifications and cryptographic RFC standards governing algorithms and key representations:
SSH Public Key Fingerprint & Converter verification · Audit standards
How to use it
- Paste an OpenSSH public-key line containing type, Base64 key blob and optional comment.
- Validate the supported key blob layout and hash the exact blob with SHA-256.
- Read SHA256: fingerprint, key type, comment and blob byte count in JSON.
Frequently asked questions
Which SSH public keys are accepted?+
It accepts OpenSSH public-key text beginning `ssh-rsa`, `ssh-ed25519`, `ssh-dss`, or `ecdsa-sha2-`. It base64-decodes the blob and checks its internal fields against the declared key type.
What does the result contain?+
For a valid key it returns `algorithm: "SHA256"`, an OpenSSH-style `fingerprint`, `format`, optional `comment`, and decoded `blobBytes`.
How is the fingerprint formatted?+
It hashes the decoded public-key blob with SHA-256 and returns `SHA256:` followed by the base64 digest with trailing `=` padding removed.
Does a matching fingerprint prove key ownership?+
No. It identifies a public-key blob for comparison. Ownership, authorization, revocation, server trust, and possession of the private key are separate questions.