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+This document describes the private key format for OpenSSH.
+
+1. Overall format
+
+The key consists of a header, a list of public keys, and
+an encrypted list of matching private keys.
+
+#define AUTH_MAGIC      "openssh-key-v1"
+
+	byte[]	AUTH_MAGIC
+	string	ciphername
+	string	kdfname
+	string	kdfoptions
+	int	number of keys N
+	string	publickey1
+	string	publickey2
+	...
+	string	publickeyN
+	string	encrypted, padded list of private keys
+
+2. KDF options for kdfname "bcrypt"
+
+The options:
+
+	string salt
+	uint32 rounds
+
+are concatenated and represented as a string.
+
+3. Unencrypted list of N private keys
+
+The list of privatekey/comment pairs is padded with the
+bytes 1, 2, 3, ... until the total length is a multiple
+of the cipher block size.
+
+	uint32	checkint
+	uint32	checkint
+	string	privatekey1
+	string	comment1
+	string	privatekey2
+	string	comment2
+	...
+	string	privatekeyN
+	string	commentN
+	char	1
+	char	2
+	char	3
+	...
+	char	padlen % 255
+
+Before the key is encrypted, a random integer is assigned
+to both checkint fields so successful decryption can be
+quickly checked by verifying that both checkint fields
+hold the same value.
+
+4. Encryption
+
+The KDF is used to derive a key, IV (and other values required by
+the cipher) from the passphrase. These values are then used to
+encrypt the unencrypted list of private keys.
+
+5. No encryption
+
+For unencrypted keys the cipher "none" and the KDF "none"
+are used with empty passphrases. The options if the KDF "none"
+are the empty string.
+
+$OpenBSD: PROTOCOL.key,v 1.1 2013/12/06 13:34:54 markus Exp $