So I used puttygen to generate a DSA private key and then exported that to the OpenSSH format and here's what I got when I ran OpenSSL's asn1parse on it: 0:d=0 hl=4 l= 443 cons: SEQUENCE 4:d=1 hl=2 l= 1 prim: INTEGER :00 7:d=1 hl=3 l= 129 prim: INTEGER :B9916796B7A3EFFD5CA36368186D0ED 193BE7FDD61CC6851174F3E9781A0C0CEA7473E528372F559A1DB2A7E049A9BEFAE2CAAC55527049 2A0CD55B59A48A53BCADD32181F519EA9E6A98EF8EF59DE314A2E69606C728F2F8DEE722B4C67BA6 8EB8A619B6006804F83740F9C74C38136522E7E83F22920AA39822FBDA0DF4D0B 139:d=1 hl=2 l= 21 prim: INTEGER :D832F5B01F075FEC0F162B91982F34D B26A0CC29 162:d=1 hl=3 l= 129 prim: INTEGER :9B73F47AEFF8E39584FD10ACF81CCD5 75C96FC5558A5C94B941EF76318D132007ACAE1EA22E95CE0B13FC7875CE4D4ED33BA639CD8C2AC9 C0A0530FB7786F584A62EBAE5985E1C26ED0D0B9FDD5E8DB0142BE182A4E5359307007060C327FEE C2F8D04EABB37D7B74076EB9BDB4885F627DE85708D5BDBF5177A05721E09A367 294:d=1 hl=3 l= 128 prim: INTEGER :6BD9267D2D1E4546EE05F6CD087F311 93C0EEB13B1E139F5072E900AB2EEF68EEC28BF4D7D6CAE4DEE59005F00BAE07343EE520C217FF6E 7880DC788E4555F78CCB5E89A10CDC71A663DA696C5BC34E296CEB3518D65A79BF00B6D592B1399A 9F0D79AE3F3FB445EE1F2B4B72515F036C8E1D5C7FAD336FD3503874645C5C264 425:d=1 hl=2 l= 20 prim: INTEGER :15295A12325E5F1A6F7243B7BB3BE74 6FE7B76E9 My question is... where is this format described? What does the first 0 integer value mean for example? I guess I could look in the puttygen source code but is there an RFC describing this format or something?