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POLength of data to hash for PGP
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  1. POLength of data to hash for PGP
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    copied!<p>I have finally managed to verify some simple PGP signed message blocks. However, I discovered that for some reason, my implementation limits me to verifying data that is 9-16 bytes long. no less. no more. </p> <p>is there some instruction somewhere (<a href="http://tools.ietf.org/pdf/rfc4880.pdf" rel="nofollow">RFC4880</a> or elsewhere) that specifies how to deal with plaintext data of any length? maybe there is some sort of padding i missed? pkcs1?</p> <p>I am pretty sure i formatted the data to hash properly, since the instructions in RFC 4880 sec 5.2.4 say for text documents, just replace all <code>\n</code> with <code>\r\n</code> and add a trailer. since my test values were single lines of data, nothing had to be replaced</p> <p>all of these values are in base 10 unless otherwise noted:</p> <pre><code>// DSA public key values p = 175466718616740411615640156350265486163809613514213656685227237159351776260193236923030228927905671867677337184318134702903960237546408302010360724274436019639502405323187799029742776686067449287558904042137172927936686590837020160292525250748155580652384740664931255981772117478967314777932252547256795892071 q = 809260232002608708872165272150356204306578772713 g = 127751900783328740354741342100721884490035793278553520238434722215554870393020469115393573782393994875216405838455564598493958342322790638050051759023658096740912555025710033120777570527002197424160086000659457154926758682221072408093235236853997248304424303705425567765059722098677806247252106481642577996274 y = 172935968966072909036304664996424500241381878537444332146572958203083745609400290814117451480512268901233962890933482206538294509037615827035398352528065134903071886710296983781453184598843331365336270501467458073523376152406987560592548479865116940266729198119357206749848310472131186772143408998928864559411 </code></pre> <p>not working:</p> <pre><code>-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 abcd -----BEGIN PGP SIGNATURE----- Version: BCPG v1.39 iFsEARECABsFAk/tB28UHGFiYyA8bWFrY21AYWFhLmNvbT4ACgkQMFIlRc933Ya2 RwCfdMyI08Iz0rDXVHOPlGA3s5Y9j/8An2He7+hHjWfGJNoOJT7gAxqJaoLo =I2rT -----END PGP SIGNATURE----- data hashed (in hex): 6162636404011102001b05024fed076f141c616263203c6d616b636d406161612e636f6d3e04ff00000021 r = 666804200764671083282351405489424949903645052927 s = 558743769080942454889260816818443017172325925608 w = 702955297882281869313155599553522395227576660460 // s^-1 mod q u1 = 190417717173929082607343542521304347388874234334 u2 = 306786785479358548892951170619047936651163362761 v = g^u1 * y^u2 % p % q = 737052148656331043521702886300418501784667890334 v != r </code></pre> <p>working:</p> <pre><code>-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 0123456789abcdef -----BEGIN PGP SIGNATURE----- Version: BCPG v1.39 iFsEARECABsFAk/tCE0UHGFiYyA8bWFrY21AYWFhLmNvbT4ACgkQMFIlRc933YYG IQCfercgPsXFnah6otgQdEMbv9OeCgIAnRIyOLirbqSlBugBT6Ex/Adz4+7L =bzab -----END PGP SIGNATURE----- data hashed (in hex): 3031323334353637383961626364656604011102001b05024fed084d141c616263203c6d616b636d406161612e636f6d3e04ff00000021 r = 700580719365380086754774917458461236187098909186 s = 103881812262595813943381509986903840453887782603 w = 178510125628083028184051840492924307896586330444 // s^-1 mod q u1 = 78831508775508876446567239486098677466912246622 u2 = 572875590470993668032596348682349224460207395691 v = g^u1 * y^u2 % p % q = 700580719365380086754774917458461236187098909186 v == r </code></pre> <p>what data did i not include in the hash / what did i do wrong?</p> <p>EDIT: here is the public key as requested, even though the relevant values have been posted already)</p> <pre><code>-----BEGIN PGP PUBLIC KEY BLOCK----- Version: BCPG v1.39 mQGiBE5B0h8RBAD533Z5bK1IpBx02QyQL0QoJE4uFRIMGDiwXuwmZzVl+R7Vlurd GRLsCCbE6vOOh7XQVZGzLEBy9WNzZ9m+EbCfSVAYkjS6FhLws6hG6irrnS+b3JBf gFJ8vNGF9Z7bhx+7y7NBk0IMyWkGnUkcnav73t5FQUI2faEBN4c/yAGJZwCgjcB7 3akWk9XVWvTCsiMXxpyvkukEALXsvB6cOoFEtQq9cQHjP63fBlvD94dhhMiM0cH6 hW9JotxdK+cxFGG9ZIWgoN2PWbMJka/H4W5EL6tS+YiNAR7I1Ozkt6X16GjnQUzZ MlSpleK+KiKVN2anRaPEoOIinHrE3ZXd6QlJ/4+OJn4IVWmSEaJpFf4QNgvEu4rh xinyBAD2RNzREOA+wpnFZ4lDt9NZXmXdxQME/l0J9XcvWhpGsxA/MATQKImy7N49 7GT/M38F+TrpBobag1O3buE99fOLyws4Tbc+sZMdHxoiGZDAIRNQS2rv475E6ktj 7vd5CYvOkA6+8sX1+hPcNlkHtHB1OFkJRsYp6k0zkyC9adjBM7QTYWJjIDxtYWtj bUBhYWEuY29tPohGBBMRAgAGBQJOQdIfAAoJEDBSJUXPd92GRSQAoItbtbToOg7a /hcg2sA/aBEQNwuxAKCGR69vmSoCWoBP5waPk0UsjM3BSbjMBE5B0h8QAgCUlP7A lfO4XuKGVCs4NvyBpd0KA0m0wjndOHRNSIz44x24vLfTO0GrueWjPMqRRLHO8zLJ S/BXO/BHo6ypjN87Af0VPV1hcq20MEW2iujh3hBwthNwBWhtKdPXOndJGZaB7lsh LJuWv9z6WyDNXj/SBEiV1gnPm0ELeg8Syhy5pCjMAf9QHehP2eCFqfEwTAnaOlA6 CU+rYHKPZaI9NUwCA7qD2d93/l08/+ZtFvejZW1RWrJ8qfLDRtlPgRzigoF/CXbR iEYEGBECAAYFAk5B0h8ACgkQMFIlRc933YZRrACfUnWTjHHN+QsEEoJrwRvFmvzj bR4An24pTpeeN+I6R59O/sdmYsAhjULX =sStS -----END PGP PUBLIC KEY BLOCK----- </code></pre>
 

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