Linux с openssl rsa

Содержание

openssl/RSA — Using a Public key to decrypt
Open SSL
DESCRIPTION
OPTIONS
NOTES
EXAMPLES
BUGS
SEE ALSO
HISTORY
COPYRIGHT
master manpages
This manpage

openssl/RSA — Using a Public key to decrypt

I’m looking to secure the software update procedure for a little device I’m maintaining that runs Linux. I want to generate an md5sum of the update package’s contents and then encrypt that hash with a private key before sending it out to the customer. When they load the update, the device should then decrypt the hash, verify it, and proceed with installation of the package. I’m trying to do this with OpenSSL and RSA. I found this thread, and was discouraged. I then found this thread and wondered how Perl gets around the purported impossibility of it all. I’m doing this in C, so perhaps there’s a parallel function in an SSL library somewhere? So my question really is: can I force command line Linux to take a public key as the decryption input, or perhaps use C to circumvent that limitation? Thanks in advance, all.

Sidenote: you encrypt with public keys and decrypt with private keys. You can also sign with a private key (which, for RSA, is identical to decryption) and verify with a public key (which, for RSA, is identical to encryption).

Thank you. Your comment helped to clarify the answer. Also, when I ran the commands in the answer (signing and verifying) the output of the signing looked encrypted and the output of the verification was plain text. I don’t understand how what you said works, then, unfortunately. How can decryption (signing) look like garbled text while encryption (verifying) looks clean?

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RSA encryption and decryption are inverses of each other. They can be run in any order. So, for a message, M , Encrypt(Decrypt(M)) == M and Decrypt(Encrypt(M)) == M .

Oh, of course. So I take it the vocabulary choice in RSA is really more to indicative which keys are used for what than it is to indicate what the output will look like. Thanks again.

Источник

Open SSL

openssl rsa [-help] [-inform DER|PEM|P12|ENGINE] [-outform DER|PEM] [-in filename|uri] [-passin arg] [-out filename] [-passout arg] [-aes128] [-aes192] [-aes256] [-aria128] [-aria192] [-aria256] [-camellia128] [-camellia192] [-camellia256] [-des] [-des3] [-idea] [-text] [-noout] [-modulus] [-traditional] [-check] [-pubin] [-pubout] [-RSAPublicKey_in] [-RSAPublicKey_out] [-pvk-strong] [-pvk-weak] [-pvk-none] [-engine id] [-provider name] [-provider-path path] [-propquery propq]

DESCRIPTION

This command processes RSA keys. They can be converted between various forms and their components printed out.

OPTIONS

Print out a usage message.

-inform DER|PEM|P12|ENGINE

The key input format; unspecified by default. See openssl-format-options(1) for details.

-outform DER|PEM

The key output format; the default is PEM. See openssl-format-options(1) for details.

When writing a private key, use the traditional PKCS#1 format instead of the PKCS#8 format.

-in filename|uri

This specifies the input to read a key from or standard input if this option is not specified. If the key is encrypted a pass phrase will be prompted for.

-passin arg, -passout arg

The password source for the input and output file. For more information about the format of arg see openssl-passphrase-options(1).

This specifies the output filename to write a key to or standard output if this option is not specified. If any encryption options are set then a pass phrase will be prompted for. The output filename should not be the same as the input filename.

-aes128, -aes192, -aes256, -aria128, -aria192, -aria256, -camellia128, -camellia192, -camellia256, -des, -des3, -idea

These options encrypt the private key with the specified cipher before outputting it. A pass phrase is prompted for. If none of these options is specified the key is written in plain text. This means that this command can be used to remove the pass phrase from a key by not giving any encryption option is given, or to add or change the pass phrase by setting them. These options can only be used with PEM format output files.

Prints out the various public or private key components in plain text in addition to the encoded version.

This option prevents output of the encoded version of the key.

This option prints out the value of the modulus of the key.

This option checks the consistency of an RSA private key.

By default a private key is read from the input. With this option a public key is read instead. If the input contains no public key but a private key, its public part is used.

By default a private key is output: with this option a public key will be output instead. This option is automatically set if the input is a public key.

-RSAPublicKey_in, -RSAPublicKey_out

Like -pubin and -pubout except RSAPublicKey format is used instead.

Enable ‘Strong’ PVK encoding level (default).

Enable ‘Weak’ PVK encoding level.

Don’t enforce PVK encoding.

-provider name -provider-path path -propquery propq

NOTES

The openssl-pkey(1) command is capable of performing all the operations this command can, as well as supporting other public key types.

EXAMPLES

The documentation for the openssl-pkey(1) command contains examples equivalent to the ones listed here.

To remove the pass phrase on an RSA private key:

openssl rsa -in key.pem -out keyout.pem

To encrypt a private key using triple DES:

openssl rsa -in key.pem -des3 -out keyout.pem

To convert a private key from PEM to DER format:

openssl rsa -in key.pem -outform DER -out keyout.der

To print out the components of a private key to standard output:

openssl rsa -in key.pem -text -noout

To just output the public part of a private key:

openssl rsa -in key.pem -pubout -out pubkey.pem

Output the public part of a private key in RSAPublicKey format:

openssl rsa -in key.pem -RSAPublicKey_out -out pubkey.pem

BUGS

There should be an option that automatically handles .key files, without having to manually edit them.

HISTORY

The -engine option was deprecated in OpenSSL 3.0.

COPYRIGHT

Licensed under the Apache License 2.0 (the «License»). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at https://www.openssl.org/source/license.html.

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