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Does GPG compress by default?
By default GPG will compress the content of encrypted message, which contains a variable part in addition to the payload. Therefore the size of the encrypted message may vary even when the payload does not change.
Does PGP encryption increase file size?
Inserting a new line every 64 characters to make it easier to read (as is done by ASCII armor in openssl, GPG, PGP) will increase the size by 65/64. Combining these two effects results in the new file being (4/3)*(65/64) = 135.4% of the size of the original or an increase in file size of 35.4%.
Are PGP files compressed?
PGP is a hybrid cryptosystem. When a user encrypts plaintext with PGP, PGP first compresses the plaintext. Data compression saves modem transmission time and disk space and, more importantly, strengthens cryptographic security. Once the data is encrypted, the session key is then encrypted to the recipient’s public key.
Is it safe to use none in GPG?
Using any algorithm other than ZIP or “none” will make the message unreadable with PGP. In general, you do not want to use this option as it allows you to violate the OpenPGP standard. –personal-compress-preferences is the safe way to accomplish the same thing.
Is it possible to compress data after encryption?
If you compress after encryption and the compression does any good (i.e. it really reduces the length by a non-negligible amount) then you can ditch the encryption, it is awfully weak. Encrypted text ought to be indistinguishable from randomness; even badly encrypted data cannot usually be compressed.
Which is the best compression algorithm for PGP?
Use compression algorithm name. “zlib” is RFC-1950 ZLIB compression. “zip” is RFC-1951 ZIP compression which is used by PGP. “bzip2” is a more modern compression scheme that can compress some things better than zip or zlib, but at the cost of more memory used during compression and decompression. “uncompressed” or “none” disables compression.
What happens if there is no secret key in GPG?
This option may be given multiple times. In this case, the last key for which a secret key is available is used. If there is no secret key available for any of the specified values, GnuPG will not emit an error message but continue as if this option wasn’t given.