Charles,
thank you for reply. I studied those documents carefully bot havent found
yet a solution.
rfc3280.txt appendix C does not describe public key format.
PKCS #1 v2.1: RSA Cryptography Standard does not not describe data storage
exact format.
The hex dump of my public.der file looks like:
00: 30 81 9D 30 0D 06 09 2A ¦ 86 48 86 F7 0D 01 01 01 0üØ0. *åHå"...
10: 05 00 03 81 8B 00 30 81 ¦ 87 02 81 81 00 B0 6D 8D ür 0ücüü _mZ
20: 8D 76 FB DA B6 91 A2 EA ¦ 11 DB 8A C2 92 AC 50 59 Zv¹-CæóL-R-ƼPY
30: 83 30 39 87 F7 51 5C 1B ¦ F5 1B 5C 4D 83 5C 71 A4 a09c"Q\§\Ma\qz
40: 5D 19 B2 1F 24 2E 0B 7F ¦ 5E C1 CF E9 93 3D F3 7B ]_ $. ^-Zko=¾{
50: 1B 1F 60 74 B5 68 93 83 ¦ F4 C8 55 18 3E BB 97 73 `tAhoa¶+U>+Ss
60: BC 8C 27 8E 70 7C 89 13 ¦ 26 B0 13 55 57 67 F7 3E +i'Äp|e&_UWg">
70: 6B 07 FA C9 58 57 36 0E ¦ D7 9D 5A 24 A3 4A F5 8A k·+XW6uØZ$ZJ§R
80: D5 A3 62 A1 C2 18 12 90 ¦ 35 85 F7 34 18 BD 1D F1 sZbI-É5g"4I ±
90: 37 5C 0D 29 48 E2 C7 FC ¦ 6A AD 55 D2 EB 02 01 03 7\)HOU³jLUel
The 1024 bit modulus starts at bytes 00 B0 6D and ends with 55 D2 EB
After that It seems that 02 01 03 is constant suffix at the end of .der
file.
What is the meaning of the file header bytes ?
Where the modulus length is stored ?
Where is the publix exponent (03) stored ?
Can you point me any documentation of the openssl source code file where I
can find information about this format ?
Thanks,
Andrus.
----- Original Message -----
From: "Charles B Cranston" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, December 14, 2004 10:35 PM
Subject: Re: DER public key file structure
> DER is short for ASN.1 Distinguished Encoding Rules. The actual
> format of certificates and things are standardized by X.500 but
> these documents are expensive, so the Internet RFC people have
> reprinted the information in a series of documents. Take a look
> at ftp://www.ietf.org/rfc/rfc3280.txt particularly the examples
> in Appendix C for the DER formats for certificates.
>
> As for keys, I think the standards document are the PKCS documents
> which can be found at http://www.rsasecurity.com/rsalabs
> look on the left for PKCS and get PKCS #1 RSA Cryptography Standard.
> Look in chapter 11 ASN.1 syntax
> 11.1 Key representations
> 11.1.1 Public-key syntax
>
> I think this is right -- good luck!
>
> Andrus wrote:
> > I need to decrypt RSA signature using RSA public key.
> > Thanks to Nils Larsch reply I discovered that the following command can
be
> > used for this:
> >
> > openssl rsautl -verify -in sig.bin -inkey public.der -pubin -keyform
> > DER -out signout.bin
> >
> > I have a RSA 1024 bits modulus and exponent 3
> >
> > I need to create a public.der file (160 bytes) from this data to be
passed
> > to openssl using not a C language.
> >
> > I looked into openssl sources but havent yet found DER file structure
> > description.
> >
> > Where I can found the DER public file structure description which this
> > command accepts ?
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