OpenSSL Signing Documents with RSA Keys

Q

What is the process of signing a document with RSA keys using OpenSSL commands? I was told to deliver a document with digital signature.

✍: FYIcenter.com

A

Here are steps your need to follow to sign a document with your RSA private key using OpenSSL commands:

1. Get the document to be signed ready.

2. Generate a digest string from the document using "md5", "sha1", or "dgst" OpenSSL commands.

3. Select an RSA private key to be used to sign the document.

4. Sign (encrypt) the digest with the RSA private key using the "rsautl sign" command.

5. Extract the RSA public key from the RSA private key with "pkey -pubout" command

6. Send the document, the signed digest, and the RSA public key together as the "signed document".

The diagram below shows you the document signing process:
OpenSSL Commands to Sign Documents

⇒ OpenSSL "rsautl -sign" - RSA Signature Generation

⇐ OpenSSL "rsautl -oaep" - OAEP Padding Option

⇑ OpenSSL "rsautl" Command for RSA Keys

⇑⇑ OpenSSL Tutorials

2017-04-04, ∼3600🔥, 0💬

OpenSSL "rsautl -verify" - RSA Signature Verification
What is the purpose of the OpenSSL "rsautl -verify" command? Can I use it to verify a signed document? Yes, you can use OpenSSL "rsautl -verify" command to verify a signed document. But you need other OpenSSL commands to generate a digest from the document first. For example, you received 3 files as... 2017-03-25, ≈12🔥, 0💬

OpenSSL "rsautl -encrypt -raw" - No Padding
Can I use OpenSSL "rsautl" command to encrypt data without any padding? Yes, you can encrypt data without any padding using the OpenSSL "rsautl -encrypt -raw" command. But you need to remember the following: No padding requires the input data to be the same size as the RSA key. No padding requires t... 2017-04-28, ≈10🔥, 0💬

OpenSSL "rsautl -sign" - RSA Signature Generation
What is the purpose of the OpenSSL "rsautl -sign" command? Can I use it to sign a document? Yes, you can use OpenSSL "rsautl -sign" command to sign a document. But you need other OpenSSL commands to generate a digest from the document first as shown in the following test: C:\Users\fyicenter>d... 2017-04-04, ∼9548🔥, 0💬

OpenSSL "rsautl -encrypt -raw" - Data Too Large Error
Why am I getting the "data too large for key size" error with OpenSSL "rsautl -encrypt -raw" command? My input data is the same size as the RSA key and I am using no padding. In most case, you should be able to use the OpenSSL "rsautl -encrypt -raw" command to encrypt input data of the same size as ... 2017-04-22, ∼6575🔥, 0💬

OpenSSL "rsautl -encrypt" vs. "rsautl -sign"
What is the difference between "rsautl -encrypt" and "rsautl -sign" commands? There are 2 differences between "rsautl -encrypt" and "rsautl -sign" commands: 1. "rsautl -encrypt" and "rsautl -sign" commands take different RSA keys: "rsautl -encrypt" only accepts an RSA public key and performs RSA enc... 2017-03-25, ∼6141🔥, 0💬

OpenSSL "rsautl" Using OAEP Padding
What is the OAEP padding schema used in OpenSSL "rsautl" command? OAEP (Optimal Asymmetric Encryption Padding), also called PKCS#1 2.0, is a padding standard specified in RFC3447 "PKCS #1: RSA Encryption, Version 1.5" proposed by RSA Laboratories in 1998. OAEP padding can be illustrated by the diagr... 2017-04-22, ∼5800🔥, 0💬

OpenSSL "rsautl" - PKCS#1 v1.5 Padding Size
Whet is the PKCS#1 v1.5 padding size with OpenSSL "rsautl -encrypt" command? I want to know the largest size of data that I can encrypt with my RSA key. The minimum padding size of PKCS#1 v1.5 padding schema is 11 bytes which contains at least 8 bytes of random string. So if you are using the "-pkcs... 2017-04-28, ∼5367🔥, 0💬

OpenSSL "rsautl -encrypt" vs. "rsautl -verify"
What is the difference between "rsautl -encrypt" and "rsautl -verify" commands? There is only 1 difference between "rsautl -encrypt" and "rsautl -verify" commands: 1. "rsautl -encrypt" and "rsautl -verify" commands apply PKCS#1 v1.5 padding differently: "rsautl -encrypt" adds PKCS#1 v1.5 padding bef... 2017-03-11, ∼4485🔥, 0💬

OpenSSL Signing Documents with RSA Keys
What is the process of signing a document with RSA keys using OpenSSL commands? I was told to deliver a document with digital signature. Here are steps your need to follow to sign a document with your RSA private key using OpenSSL commands: 1. Get the document to be signed ready. 2. Generate a diges... 2017-04-04, ∼3601🔥, 0💬

All rights in the contents of this web site are reserved by the individual author. fyicenter.com does not guarantee the truthfulness, accuracy, or reliability of any contents.