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testssl.sh
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Fix public key length calculation 

This PR fixes a minor bug in get_pub_key_size(). If the key size is being determined manually and length encoding requires 4 bytes, then the current code computes the length incorrectly. This is a very insignificant bug, since does not apply to RSA or ECC keys, and the key would have to be at least 16 megabytes long for it to require 4 bytes to encode.

This PR also cleans up get_pub_key_size() a bit by replacing `i=$i+...` with `i+=...` and by enclosing math in `$(( ... ))`.
This commit is contained in:
David Cooper 2020-02-04 14:55:53 -05:00 committed by GitHub
parent e9430bdd23
commit 3025d92ebf
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 29 additions and 29 deletions
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testssl.sh
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@ -10503,83 +10503,83 @@ get_pub_key_size() {
i=2
len1="0x${pubkey:i:2}"
if [[ $len1 -lt 0x80 ]]; then
i=$i+2
i+=2
else
len1=$len1-0x80
i=$i+2*$len1+2
len1=$((len1-0x80))
i+=$((2*len1+2))
fi
# Skip over algorithm field
i=$i+2
i+=2
len1="0x${pubkey:i:2}"
i=$i+2
i+=2
if [[ $len1 -lt 0x80 ]]; then
i=$i+2*$len1
i+=$((2*len1))
else
case $len1 in
129) len="0x${pubkey:i:2}" ;;
130) len="0x${pubkey:i:2}"
i=$i+2
i+=2
len=256*$len+"0x${pubkey:i:2}"
;;
131) len="0x${pubkey:i:2}"
i=$i+2
i+=2
len=256*$len+"0x${pubkey:i:2}"
i=$i+2
i+=2
len=256*$len+"0x${pubkey:i:2}"
;;
132) len="0x${pubkey:i:2}"
i=$i+2
i+=2
len=256*$len+"0x${pubkey:i:2}"
i=$i+2
i+=2
len=256*$len+"0x${pubkey:i:2}"
i=$i+2
i+=2
len=256*$len+"0x${pubkey:i:2}"
;;
esac
i=$i+2+2*$len
i+=$((2+2*len))
fi
# Next is the public key BIT STRING. Skip over tag, length, and number of unused bits.
i=$i+2
i+=2
len1="0x${pubkey:i:2}"
if [[ $len1 -lt 0x80 ]]; then
i=$i+4
i+=4
else
len1=$len1-0x80
i=$i+2*$len1+4
len1=$((len1-0x80))
i+=$((2*len1+4))
fi
# Now get the length of the public key
i=$i+2
i+=2
len1="0x${pubkey:i:2}"
i=$i+2
i+=2
if [[ $len1 -lt 0x80 ]]; then
len=$len1
else
case $len1 in
129) len="0x${pubkey:i:2}" ;;
130) len="0x${pubkey:i:2}"
i=$i+2
i+=2
len=256*$len+"0x${pubkey:i:2}"
;;
131) len="0x${pubkey:i:2}"
i=$i+2
i+=2
len=256*$len+"0x${pubkey:i:2}"
i=$i+2
i+=2
len=256*$len+"0x${pubkey:i:2}"
;;
132) len="0x${pubkey:i:2}"
i=$i+2
len=256*"0x${pubkey:i:2}"
i=$i+2
len=256*"0x${pubkey:i:2}"
i=$i+2
len=256*"0x${pubkey:i:2}"
i+=2
len=256*$len+"0x${pubkey:i:2}"
i+=2
len=256*$len+"0x${pubkey:i:2}"
i+=2
len=256*$len+"0x${pubkey:i:2}"
;;
esac
fi
len=8*$len # convert from bytes to bits
len=$((8*len)) # convert from bytes to bits
pubkeybits="$(printf "%d" $len)"
echo "Server public key is $pubkeybits bit" >> $TMPFILE
fi