Interface PuttyKeyPairResourceParser<PUB extends PublicKey, PRV extends PrivateKey>

Type Parameters:

PUB - Generic public key type

PRV - Generic private key type

All Superinterfaces:

IdentityResourceLoader<PUB,PRV>, KeyPairResourceLoader, KeyPairResourceParser, KeyTypeNamesSupport

All Known Implementing Classes:

AbstractPuttyKeyDecoder, DSSPuttyKeyDecoder, ECDSAPuttyKeyDecoder, EdDSAPuttyKeyDecoder, RSAPuttyKeyDecoder

public interface PuttyKeyPairResourceParser<PUB extends PublicKey, PRV extends PrivateKey>
extends IdentityResourceLoader<PUB,PRV>, KeyPairResourceParser

Loads a KeyPair from PuTTY's ".ppk" file.

Note(s):

• The file appears to be a text file but it doesn't have a fixed encoding like UTF-8. We use UTF-8 as the default encoding - since the important part is all ASCII, this shouldn't really hurt the interpretation of the key.
• Based on code from Kohsuke's Trilead Putty Extension
• Encrypted keys requires AES-256-CBC support, which is available only if the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files are installed

Sample PuTTY file format

PuTTY-User-Key-File-2: ssh-rsa
Encryption: none
Comment: rsa-key-20080514
Public-Lines: 4
AAAAB3NzaC1yc2EAAAABJQAAAIEAiPVUpONjGeVrwgRPOqy3Ym6kF/f8bltnmjA2
BMdAtaOpiD8A2ooqtLS5zWYuc0xkW0ogoKvORN+RF4JI+uNUlkxWxnzJM9JLpnvA
HrMoVFaQ0cgDMIHtE1Ob1cGAhlNInPCRnGNJpBNcJ/OJye3yt7WqHP4SPCCLb6nL
nmBUrLM=
Private-Lines: 8
AAAAgGtYgJzpktzyFjBIkSAmgeVdozVhgKmF6WsDMUID9HKwtU8cn83h6h7ug8qA
hUWcvVxO201/vViTjWVz9ALph3uMnpJiuQaaNYIGztGJBRsBwmQW9738pUXcsUXZ
79KJP01oHn6Wkrgk26DIOsz04QOBI6C8RumBO4+F1WdfueM9AAAAQQDmA4hcK8Bx
nVtEpcF310mKD3nsbJqARdw5NV9kCxPnEsmy7Sy1L4Ob/nTIrynbc3MA9HQVJkUz
7V0va5Pjm/T7AAAAQQCYbnG0UEekwk0LG1Hkxh1OrKMxCw2KWMN8ac3L0LVBg/Tk
8EnB2oT45GGeJaw7KzdoOMFZz0iXLsVLNUjNn2mpAAAAQQCN6SEfWqiNzyc/w5n/
lFVDHExfVUJp0wXv+kzZzylnw4fs00lC3k4PZDSsb+jYCMesnfJjhDgkUA0XPyo8
Emdk
Private-MAC: 50c45751d18d74c00fca395deb7b7695e3ed6f77

Field Summary

Fields

Modifier and Type	Field	Description
static final int	FORMAT_3_MAC_KEY_LENGTH	PUTTY key v3 MAC key length
static final String	KEY_FILE_HEADER_PREFIX
static final List<String>	KNOWN_HEADERS
static final String	NO_PRIVATE_KEY_ENCRYPTION_VALUE	Value (case insensitive) used to denote that private key is not encrypted
static final String	PPK_FILE_SUFFIX
static final String	PRIVATE_LINES_HEADER
static final String	PUBLIC_LINES_HEADER

Fields inherited from interface IdentityResourceLoader

MAX_BIGINT_OCTETS_COUNT

Fields inherited from interface KeyPairResourceLoader

MAX_CIPHER_NAME_LENGTH, MAX_KEY_COMMENT_LENGTH, MAX_KEY_TYPE_NAME_LENGTH, MAX_PRIVATE_KEY_DATA_SIZE, MAX_PUBLIC_KEY_DATA_SIZE

Fields inherited from interface KeyPairResourceParser

EMPTY

Method Summary

Modifier and Type	Method	Description
default boolean	canExtractKeyPairs(NamedResource resourceKey, List<String> lines)
static void	decodeEncryptionKey(int formatVersion, String passphrase, byte[] iv, byte[] key, Map<String,String> headers)	Converts a pass-phrase into a key, by following the conventions that PuTTY uses.
static byte[]	decodePrivateKeyBytes(byte[] encBytes, String cipherName, String cipherMode, int numBits, byte[] initVector, byte[] keyValue)
static byte[]	decodePrivateKeyBytes(int formatVersion, byte[] prvBytes, String algName, int numBits, String algMode, String password, Map<String,String> headers)
static void	deriveFormat2EncryptionKey(String passphrase, byte[] iv, byte[] key)	Uses the "legacy" KDF via SHA-1
static void	deriveFormat3EncryptionKey(String passphrase, String keyDerivationType, byte[] iv, byte[] key, Map<String,String> headers)
static byte[]	getHexArrayHeaderValue(Map<String,String> headers, String key)
static int	getIntegerHeaderValue(Map<String,String> headers, String key)
static String	getStringHeaderValue(Map<String,String> headers, String key)

Methods inherited from interface IdentityResourceLoader

getPrivateKeyType, getPublicKeyType

Methods inherited from interface KeyPairResourceLoader

loadKeyPairs, loadKeyPairs, loadKeyPairs, loadKeyPairs, loadKeyPairs, loadKeyPairs, loadKeyPairs, loadKeyPairs, loadKeyPairs, loadKeyPairs, loadKeyPairs, loadKeyPairs

Methods inherited from interface KeyTypeNamesSupport

getSupportedKeyTypes

Field Details

KEY_FILE_HEADER_PREFIX

static final String KEY_FILE_HEADER_PREFIX

See Also:

• Constant Field Values

PUBLIC_LINES_HEADER

static final String PUBLIC_LINES_HEADER

See Also:

• Constant Field Values

PRIVATE_LINES_HEADER

static final String PRIVATE_LINES_HEADER

See Also:

• Constant Field Values

PPK_FILE_SUFFIX

static final String PPK_FILE_SUFFIX

See Also:

• Constant Field Values

KNOWN_HEADERS

static final List<String> KNOWN_HEADERS

NO_PRIVATE_KEY_ENCRYPTION_VALUE

static final String NO_PRIVATE_KEY_ENCRYPTION_VALUE

Value (case insensitive) used to denote that private key is not encrypted

See Also:

• Constant Field Values

FORMAT_3_MAC_KEY_LENGTH

static final int FORMAT_3_MAC_KEY_LENGTH

PUTTY key v3 MAC key length

See Also:

• Constant Field Values

Method Details

canExtractKeyPairs

default boolean canExtractKeyPairs(NamedResource resourceKey,
 List<String> lines)
                            throws IOException,
GeneralSecurityException

Specified by:

canExtractKeyPairs in interface KeyPairResourceParser

Parameters:

resourceKey - A hint as to the origin of the text lines

lines - The resource lines

Returns:

true if the parser can extract some key pairs from the lines

Throws:

IOException - If failed to process the lines

GeneralSecurityException - If failed to extract information regarding the possibility to extract the key pairs

decodePrivateKeyBytes

static byte[] decodePrivateKeyBytes(int formatVersion,
 byte[] prvBytes,
 String algName,
 int numBits,
 String algMode,
 String password,
 Map<String,String> headers)
                             throws GeneralSecurityException

Throws:

GeneralSecurityException

decodePrivateKeyBytes

static byte[] decodePrivateKeyBytes(byte[] encBytes,
 String cipherName,
 String cipherMode,
 int numBits,
 byte[] initVector,
 byte[] keyValue)
                             throws GeneralSecurityException

Throws:

GeneralSecurityException

decodeEncryptionKey

static void decodeEncryptionKey(int formatVersion,
 String passphrase,
 byte[] iv,
 byte[] key,
 Map<String,String> headers)
                         throws GeneralSecurityException

Converts a pass-phrase into a key, by following the conventions that PuTTY uses. Used to decrypt the private key when it's encrypted.

Parameters:

formatVersion - The file format version

passphrase - The Password to be used as seed for the key - ignored if null/empty

iv - Initialization vector to be populated if necessary

key - Key to be populated

headers - Any extra headers found in the PPK file that might be used for KDF

Throws:

GeneralSecurityException - If cannot derive the key bytes from the password

deriveFormat3EncryptionKey

static void deriveFormat3EncryptionKey(String passphrase,
 String keyDerivationType,
 byte[] iv,
 byte[] key,
 Map<String,String> headers)
                                throws GeneralSecurityException

Throws:

GeneralSecurityException

getStringHeaderValue

static String getStringHeaderValue(Map<String,String> headers,
 String key)

getHexArrayHeaderValue

static byte[] getHexArrayHeaderValue(Map<String,String> headers,
 String key)

getIntegerHeaderValue

static int getIntegerHeaderValue(Map<String,String> headers,
 String key)

deriveFormat2EncryptionKey

static void deriveFormat2EncryptionKey(String passphrase,
 byte[] iv,
 byte[] key)
                                throws GeneralSecurityException

Uses the "legacy" KDF via SHA-1

Parameters:

passphrase - The Password to be used as seed for the key - ignored if null/empty

iv - Initialization vector to be populated if necessary

key - Key to be populated

Throws:

GeneralSecurityException - If cannot retrieve SHA-1 digest

See Also:

• How does Putty derive the encryption key in its .ppk format ?