Add 'crypto/ecies/' from commit '7c0f4a9b18d992166452d8cd32caaefd92b26386'

git-subtree-dir: crypto/ecies
git-subtree-mainline: 49a739c8d6
git-subtree-split: 7c0f4a9b18

crypto/ecies/params.go

@@ -0,0 +1,181 @@
+package ecies
+
+// This file contains parameters for ECIES encryption, specifying the
+// symmetric encryption and HMAC parameters.
+
+import (
+	"crypto"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/elliptic"
+	"crypto/sha256"
+	"crypto/sha512"
+	"fmt"
+	"hash"
+)
+
+// The default curve for this package is the NIST P256 curve, which
+// provides security equivalent to AES-128.
+var DefaultCurve = elliptic.P256()
+
+var (
+	ErrUnsupportedECDHAlgorithm   = fmt.Errorf("ecies: unsupported ECDH algorithm")
+	ErrUnsupportedECIESParameters = fmt.Errorf("ecies: unsupported ECIES parameters")
+)
+
+type ECIESParams struct {
+	Hash      func() hash.Hash // hash function
+	hashAlgo  crypto.Hash
+	Cipher    func([]byte) (cipher.Block, error) // symmetric cipher
+	BlockSize int                                // block size of symmetric cipher
+	KeyLen    int                                // length of symmetric key
+}
+
+// Standard ECIES parameters:
+// * ECIES using AES128 and HMAC-SHA-256-16
+// * ECIES using AES256 and HMAC-SHA-256-32
+// * ECIES using AES256 and HMAC-SHA-384-48
+// * ECIES using AES256 and HMAC-SHA-512-64
+
+var (
+	ECIES_AES128_SHA256 = &ECIESParams{
+		Hash:      sha256.New,
+		hashAlgo:  crypto.SHA256,
+		Cipher:    aes.NewCipher,
+		BlockSize: aes.BlockSize,
+		KeyLen:    16,
+	}
+
+	ECIES_AES256_SHA256 = &ECIESParams{
+		Hash:      sha256.New,
+		hashAlgo:  crypto.SHA256,
+		Cipher:    aes.NewCipher,
+		BlockSize: aes.BlockSize,
+		KeyLen:    32,
+	}
+
+	ECIES_AES256_SHA384 = &ECIESParams{
+		Hash:      sha512.New384,
+		hashAlgo:  crypto.SHA384,
+		Cipher:    aes.NewCipher,
+		BlockSize: aes.BlockSize,
+		KeyLen:    32,
+	}
+
+	ECIES_AES256_SHA512 = &ECIESParams{
+		Hash:      sha512.New,
+		hashAlgo:  crypto.SHA512,
+		Cipher:    aes.NewCipher,
+		BlockSize: aes.BlockSize,
+		KeyLen:    32,
+	}
+)
+
+var paramsFromCurve = map[elliptic.Curve]*ECIESParams{
+	elliptic.P256(): ECIES_AES128_SHA256,
+	elliptic.P384(): ECIES_AES256_SHA384,
+	elliptic.P521(): ECIES_AES256_SHA512,
+}
+
+func AddParamsForCurve(curve elliptic.Curve, params *ECIESParams) {
+	paramsFromCurve[curve] = params
+}
+
+// ParamsFromCurve selects parameters optimal for the selected elliptic curve.
+// Only the curves P256, P384, and P512 are supported.
+func ParamsFromCurve(curve elliptic.Curve) (params *ECIESParams) {
+	return paramsFromCurve[curve]
+
+	/*
+		switch curve {
+		case elliptic.P256():
+			return ECIES_AES128_SHA256
+		case elliptic.P384():
+			return ECIES_AES256_SHA384
+		case elliptic.P521():
+			return ECIES_AES256_SHA512
+		default:
+			return nil
+		}
+	*/
+}
+
+// ASN.1 encode the ECIES parameters relevant to the encryption operations.
+func paramsToASNECIES(params *ECIESParams) (asnParams asnECIESParameters) {
+	if nil == params {
+		return
+	}
+	asnParams.KDF = asnNISTConcatenationKDF
+	asnParams.MAC = hmacFull
+	switch params.KeyLen {
+	case 16:
+		asnParams.Sym = aes128CTRinECIES
+	case 24:
+		asnParams.Sym = aes192CTRinECIES
+	case 32:
+		asnParams.Sym = aes256CTRinECIES
+	}
+	return
+}
+
+// ASN.1 encode the ECIES parameters relevant to ECDH.
+func paramsToASNECDH(params *ECIESParams) (algo asnECDHAlgorithm) {
+	switch params.hashAlgo {
+	case crypto.SHA224:
+		algo = dhSinglePass_stdDH_sha224kdf
+	case crypto.SHA256:
+		algo = dhSinglePass_stdDH_sha256kdf
+	case crypto.SHA384:
+		algo = dhSinglePass_stdDH_sha384kdf
+	case crypto.SHA512:
+		algo = dhSinglePass_stdDH_sha512kdf
+	}
+	return
+}
+
+// ASN.1 decode the ECIES parameters relevant to the encryption stage.
+func asnECIEStoParams(asnParams asnECIESParameters, params *ECIESParams) {
+	if !asnParams.KDF.Cmp(asnNISTConcatenationKDF) {
+		params = nil
+		return
+	} else if !asnParams.MAC.Cmp(hmacFull) {
+		params = nil
+		return
+	}
+
+	switch {
+	case asnParams.Sym.Cmp(aes128CTRinECIES):
+		params.KeyLen = 16
+		params.BlockSize = 16
+		params.Cipher = aes.NewCipher
+	case asnParams.Sym.Cmp(aes192CTRinECIES):
+		params.KeyLen = 24
+		params.BlockSize = 16
+		params.Cipher = aes.NewCipher
+	case asnParams.Sym.Cmp(aes256CTRinECIES):
+		params.KeyLen = 32
+		params.BlockSize = 16
+		params.Cipher = aes.NewCipher
+	default:
+		params = nil
+	}
+}
+
+// ASN.1 decode the ECIES parameters relevant to ECDH.
+func asnECDHtoParams(asnParams asnECDHAlgorithm, params *ECIESParams) {
+	if asnParams.Cmp(dhSinglePass_stdDH_sha224kdf) {
+		params.hashAlgo = crypto.SHA224
+		params.Hash = sha256.New224
+	} else if asnParams.Cmp(dhSinglePass_stdDH_sha256kdf) {
+		params.hashAlgo = crypto.SHA256
+		params.Hash = sha256.New
+	} else if asnParams.Cmp(dhSinglePass_stdDH_sha384kdf) {
+		params.hashAlgo = crypto.SHA384
+		params.Hash = sha512.New384
+	} else if asnParams.Cmp(dhSinglePass_stdDH_sha512kdf) {
+		params.hashAlgo = crypto.SHA512
+		params.Hash = sha512.New
+	} else {
+		params = nil
+	}
+}