60 lines
1.5 KiB
Go
60 lines
1.5 KiB
Go
package pkcs8
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import (
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"bytes"
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"crypto/cipher"
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"encoding/asn1"
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)
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type cipherWithBlock struct {
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oid asn1.ObjectIdentifier
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ivSize int
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keySize int
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newBlock func(key []byte) (cipher.Block, error)
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}
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func (c cipherWithBlock) IVSize() int {
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return c.ivSize
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}
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func (c cipherWithBlock) KeySize() int {
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return c.keySize
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}
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func (c cipherWithBlock) OID() asn1.ObjectIdentifier {
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return c.oid
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}
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func (c cipherWithBlock) Encrypt(key, iv, plaintext []byte) ([]byte, error) {
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block, err := c.newBlock(key)
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if err != nil {
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return nil, err
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}
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return cbcEncrypt(block, key, iv, plaintext)
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}
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func (c cipherWithBlock) Decrypt(key, iv, ciphertext []byte) ([]byte, error) {
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block, err := c.newBlock(key)
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if err != nil {
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return nil, err
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}
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return cbcDecrypt(block, key, iv, ciphertext)
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}
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func cbcEncrypt(block cipher.Block, key, iv, plaintext []byte) ([]byte, error) {
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mode := cipher.NewCBCEncrypter(block, iv)
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paddingLen := block.BlockSize() - (len(plaintext) % block.BlockSize())
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ciphertext := make([]byte, len(plaintext)+paddingLen)
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copy(ciphertext, plaintext)
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copy(ciphertext[len(plaintext):], bytes.Repeat([]byte{byte(paddingLen)}, paddingLen))
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mode.CryptBlocks(ciphertext, ciphertext)
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return ciphertext, nil
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}
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func cbcDecrypt(block cipher.Block, key, iv, ciphertext []byte) ([]byte, error) {
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mode := cipher.NewCBCDecrypter(block, iv)
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plaintext := make([]byte, len(ciphertext))
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mode.CryptBlocks(plaintext, ciphertext)
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// TODO: remove padding
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return plaintext, nil
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}
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