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