Курнат Андрей
46 lines
1.5 KiB
Go
46 lines
1.5 KiB
Go
package dsig
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import (
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"crypto"
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"crypto/rand"
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"fmt"
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"io"
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)
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// cryptosign is a low-level function that signs a payload using a crypto.Signer.
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// If hash is crypto.Hash(0), the payload is signed directly without hashing.
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// Otherwise, the payload is hashed using the specified hash function before signing.
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//
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// rr is an io.Reader that provides randomness for signing. If rr is nil, it defaults to rand.Reader.
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func cryptosign(signer crypto.Signer, payload []byte, hash crypto.Hash, opts crypto.SignerOpts, rr io.Reader) ([]byte, error) {
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if rr == nil {
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rr = rand.Reader
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}
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var digest []byte
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if hash == crypto.Hash(0) {
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digest = payload
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} else {
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h := hash.New()
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if _, err := h.Write(payload); err != nil {
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return nil, fmt.Errorf(`failed to write payload to hash: %w`, err)
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}
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digest = h.Sum(nil)
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}
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return signer.Sign(rr, digest, opts)
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}
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// SignCryptoSigner generates a signature using a crypto.Signer interface.
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// This function can be used for hardware security modules, smart cards,
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// and other implementations of the crypto.Signer interface.
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//
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// rr is an io.Reader that provides randomness for signing. If rr is nil, it defaults to rand.Reader.
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//
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// Returns the signature bytes or an error if signing fails.
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func SignCryptoSigner(signer crypto.Signer, raw []byte, h crypto.Hash, opts crypto.SignerOpts, rr io.Reader) ([]byte, error) {
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if signer == nil {
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return nil, fmt.Errorf("dsig.SignCryptoSigner: signer is nil")
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}
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return cryptosign(signer, raw, h, opts, rr)
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}
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