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@@ -0,0 +1,137 @@
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+package crypto
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+
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+import (
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+ "bytes"
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+ "crypto/md5"
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+ "github.com/jcmturner/gokrb5/crypto/common"
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+ "github.com/jcmturner/gokrb5/crypto/rfc3961"
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+ "github.com/jcmturner/gokrb5/crypto/rfc4757"
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+ "github.com/jcmturner/gokrb5/iana/chksumtype"
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+ "github.com/jcmturner/gokrb5/iana/etypeID"
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+ "golang.org/x/crypto/md4"
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+ "hash"
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+ "io"
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+)
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+
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+//http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/8u40-b25/sun/security/krb5/internal/crypto/dk/ArcFourCrypto.java#ArcFourCrypto.encrypt%28byte%5B%5D%2Cint%2Cbyte%5B%5D%2Cbyte%5B%5D%2Cbyte%5B%5D%2Cint%2Cint%29
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+
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+// RC4HMAC implements Kerberos encryption type aes256-cts-hmac-sha1-96
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+type RC4HMAC struct {
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+}
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+
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+// GetETypeID returns the EType ID number.
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+func (e RC4HMAC) GetETypeID() int {
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+ return etypeID.RC4_HMAC
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+}
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+
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+// GetHashID returns the checksum type ID number.
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+func (e RC4HMAC) GetHashID() int {
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+ return chksumtype.KERB_CHECKSUM_HMAC_MD5
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+}
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+
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+// GetKeyByteSize returns the number of bytes for key of this etype.
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+func (e RC4HMAC) GetKeyByteSize() int {
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+ return 16
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+}
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+
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+// GetKeySeedBitLength returns the number of bits for the seed for key generation.
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+func (e RC4HMAC) GetKeySeedBitLength() int {
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+ return e.GetKeyByteSize() * 8
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+}
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+
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+// GetHashFunc returns the hash function for this etype.
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+func (e RC4HMAC) GetHashFunc() func() hash.Hash {
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+ return md5.New
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+}
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+
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+// GetMessageBlockByteSize returns the block size for the etype's messages.
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+func (e RC4HMAC) GetMessageBlockByteSize() int {
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+ return 1
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+}
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+
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+// GetDefaultStringToKeyParams returns the default key derivation parameters in string form.
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+func (e RC4HMAC) GetDefaultStringToKeyParams() string {
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+ return ""
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+}
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+
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+// GetConfounderByteSize returns the byte count for confounder to be used during cryptographic operations.
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+func (e RC4HMAC) GetConfounderByteSize() int {
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+ return 8
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+}
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+
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+// GetHMACBitLength returns the bit count size of the integrity hash.
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+func (e RC4HMAC) GetHMACBitLength() int {
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+ return md5.Size * 8
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+}
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+
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+// GetCypherBlockBitLength returns the bit count size of the cypher block.
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+func (e RC4HMAC) GetCypherBlockBitLength() int {
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+ return 8 // doesn't really apply
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+}
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+
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+// StringToKey returns a key derived from the string provided.
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+func (e RC4HMAC) StringToKey(secret string, salt string, s2kparams string) ([]byte, error) {
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+ return rfc4757.StringToKey(secret)
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+}
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+
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+// RandomToKey returns a key from the bytes provided.
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+func (e RC4HMAC) RandomToKey(b []byte) []byte {
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+ r := bytes.NewReader(b)
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+ h := md4.New()
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+ io.Copy(h, r)
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+ return h.Sum(nil)
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+}
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+
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+// EncryptData encrypts the data provided.
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+func (e RC4HMAC) EncryptData(key, data []byte) ([]byte, []byte, error) {
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+ b, err := rfc4757.EncryptData(key, data, e)
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+ return []byte{}, b, err
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+}
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+
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+// EncryptMessage encrypts the message provided and concatenates it with the integrity hash to create an encrypted message.
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+func (e RC4HMAC) EncryptMessage(key, message []byte, usage uint32) ([]byte, []byte, error) {
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+ b, err := rfc4757.EncryptMessage(key, message, usage, false, e)
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+ return []byte{}, b, err
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+}
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+
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+// DecryptData decrypts the data provided.
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+func (e RC4HMAC) DecryptData(key, data []byte) ([]byte, error) {
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+ return rfc4757.DecryptData(key, data, e)
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+}
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+
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+// DecryptMessage decrypts the message provided and verifies the integrity of the message.
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+func (e RC4HMAC) DecryptMessage(key, ciphertext []byte, usage uint32) ([]byte, error) {
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+ return rfc4757.DecryptMessage(key, ciphertext, usage, false, e)
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+}
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+
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+// DeriveKey derives a key from the protocol key based on the usage value.
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+func (e RC4HMAC) DeriveKey(protocolKey, usage []byte) ([]byte, error) {
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+ return rfc4757.HMAC(protocolKey, usage), nil
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+}
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+
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+// DeriveRandom generates data needed for key generation.
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+func (e RC4HMAC) DeriveRandom(protocolKey, usage []byte) ([]byte, error) {
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+ return rfc3961.DeriveRandom(protocolKey, usage, e)
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+}
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+
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+// VerifyIntegrity checks the integrity of the plaintext message.
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+func (e RC4HMAC) VerifyIntegrity(protocolKey, ct, pt []byte, usage uint32) bool {
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+ return rfc4757.VerifyIntegrity(protocolKey, pt, ct, e)
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+}
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+
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+// GetChecksumHash returns a keyed checksum hash of the bytes provided.
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+func (e RC4HMAC) GetChecksumHash(protocolKey, data []byte, usage uint32) ([]byte, error) {
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+ return common.GetHash(data, protocolKey, common.GetUsageKc(usage), e)
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+}
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+
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+// VerifyChecksum compares the checksum of the message bytes is the same as the checksum provided.
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+func (e RC4HMAC) VerifyChecksum(protocolKey, data, chksum []byte, usage uint32) bool {
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+ checksum, err := rfc4757.Checksum(protocolKey, usage, data)
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+ if err != nil {
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+ return false
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+ }
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+ if !bytes.Equal(checksum, chksum) {
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+ return false
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+ }
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+ return true
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+}
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