Why does the decode function of the segwit bech32 encoder/decoder take a hrp (human readable part) as input?
Looking at the code referenced in bip-0173, specifically for example here:
https://github.com/sipa/bech32/blob/master/ref/javascript/segwit_addr.js
function decode (hrp, addr) {
var dec = bech32.decode(addr);
if (dec === null || dec.hrp !== hrp || dec.data.length < 1 || dec.data[0] > 16) {
return null;
}
...
I understand that this is an error checking statement, but why check a (user?) inputted hrp vs the decoded hrp from bech32.decode?
Also I'm assuming that the "dec.data[0] > 16" check is to make sure that the byte at index zero doesn't exceed a value of 16, which would be invalid hex. Is this correct?
segregated-witness bech32-address
asked yesterday
kawthuldrokkawthuldrok
488
add a comment |
Looking at the code referenced in bip-0173, specifically for example here:
https://github.com/sipa/bech32/blob/master/ref/javascript/segwit_addr.js
function decode (hrp, addr) {
var dec = bech32.decode(addr);
if (dec === null || dec.hrp !== hrp || dec.data.length < 1 || dec.data[0] > 16) {
return null;
}
...
I understand that this is an error checking statement, but why check a (user?) inputted hrp vs the decoded hrp from bech32.decode?
Also I'm assuming that the "dec.data[0] > 16" check is to make sure that the byte at index zero doesn't exceed a value of 16, which would be invalid hex. Is this correct?
segregated-witness bech32-address
asked yesterday
kawthuldrokkawthuldrok
488
add a comment |
Looking at the code referenced in bip-0173, specifically for example here:
https://github.com/sipa/bech32/blob/master/ref/javascript/segwit_addr.js
function decode (hrp, addr) {
var dec = bech32.decode(addr);
if (dec === null || dec.hrp !== hrp || dec.data.length < 1 || dec.data[0] > 16) {
return null;
}
...
I understand that this is an error checking statement, but why check a (user?) inputted hrp vs the decoded hrp from bech32.decode?
Also I'm assuming that the "dec.data[0] > 16" check is to make sure that the byte at index zero doesn't exceed a value of 16, which would be invalid hex. Is this correct?
segregated-witness bech32-address
asked yesterday
kawthuldrokkawthuldrok
488
Looking at the code referenced in bip-0173, specifically for example here:
https://github.com/sipa/bech32/blob/master/ref/javascript/segwit_addr.js
function decode (hrp, addr) {
var dec = bech32.decode(addr);
if (dec === null || dec.hrp !== hrp || dec.data.length < 1 || dec.data[0] > 16) {
return null;
}
...
I understand that this is an error checking statement, but why check a (user?) inputted hrp vs the decoded hrp from bech32.decode?
Also I'm assuming that the "dec.data[0] > 16" check is to make sure that the byte at index zero doesn't exceed a value of 16, which would be invalid hex. Is this correct?
segregated-witness bech32-address
segregated-witness bech32-address
asked yesterday
kawthuldrokkawthuldrok
488
asked yesterday
kawthuldrokkawthuldrok
488
asked yesterday
kawthuldrokkawthuldrok
488
asked yesterday
kawthuldrokkawthuldrok
488
asked yesterday
kawthuldrokkawthuldrok
488
488
add a comment |
add a comment |
2 Answers
2
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votes
The HRP is part of the bech32 encoded string, and in the bech32 decoding API, it is returned along with the payload by the decoder, after checking the checksum.
We still want to compare it with the expected HRP in BIP173, which encodes the chain the software is operating on.
Otherwise you could have a testnet node that accepts mainnet BIP173 addresses or the other way around.
answered yesterday
Pieter WuillePieter Wuille
45.6k393154
add a comment |
I'm assuming that the "dec.data[0] > 16" check is to make sure that the byte at index zero doesn't exceed a value of 16, which would be invalid hex. Is this correct?
No, it's because only versions 0 - 16 are specified. Other versions might behave entirely differently. (As an aside, if it were a comparison for the sake of clamping to the range of a single hex character the test would be >15 not >16).
answered yesterday
G. MaxwellG. Maxwell
3,4681630
Ah, I see now. Also, dec.data[0] is a byte's worth of data (two hex chars), which can hold 256 different states.
– kawthuldrok
49 mins ago
add a comment |
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2 Answers
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2 Answers
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active
oldest
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The HRP is part of the bech32 encoded string, and in the bech32 decoding API, it is returned along with the payload by the decoder, after checking the checksum.
We still want to compare it with the expected HRP in BIP173, which encodes the chain the software is operating on.
Otherwise you could have a testnet node that accepts mainnet BIP173 addresses or the other way around.
answered yesterday
Pieter WuillePieter Wuille
45.6k393154
add a comment |
The HRP is part of the bech32 encoded string, and in the bech32 decoding API, it is returned along with the payload by the decoder, after checking the checksum.
We still want to compare it with the expected HRP in BIP173, which encodes the chain the software is operating on.
Otherwise you could have a testnet node that accepts mainnet BIP173 addresses or the other way around.
answered yesterday
Pieter WuillePieter Wuille
45.6k393154
add a comment |
The HRP is part of the bech32 encoded string, and in the bech32 decoding API, it is returned along with the payload by the decoder, after checking the checksum.
We still want to compare it with the expected HRP in BIP173, which encodes the chain the software is operating on.
Otherwise you could have a testnet node that accepts mainnet BIP173 addresses or the other way around.
answered yesterday
Pieter WuillePieter Wuille
45.6k393154
The HRP is part of the bech32 encoded string, and in the bech32 decoding API, it is returned along with the payload by the decoder, after checking the checksum.
We still want to compare it with the expected HRP in BIP173, which encodes the chain the software is operating on.
Otherwise you could have a testnet node that accepts mainnet BIP173 addresses or the other way around.
answered yesterday
Pieter WuillePieter Wuille
45.6k393154
answered yesterday
Pieter WuillePieter Wuille
45.6k393154
answered yesterday
Pieter WuillePieter Wuille
45.6k393154
answered yesterday
Pieter WuillePieter Wuille
45.6k393154
45.6k393154
add a comment |
add a comment |
I'm assuming that the "dec.data[0] > 16" check is to make sure that the byte at index zero doesn't exceed a value of 16, which would be invalid hex. Is this correct?
No, it's because only versions 0 - 16 are specified. Other versions might behave entirely differently. (As an aside, if it were a comparison for the sake of clamping to the range of a single hex character the test would be >15 not >16).
answered yesterday
G. MaxwellG. Maxwell
3,4681630
Ah, I see now. Also, dec.data[0] is a byte's worth of data (two hex chars), which can hold 256 different states.
– kawthuldrok
49 mins ago
add a comment |
I'm assuming that the "dec.data[0] > 16" check is to make sure that the byte at index zero doesn't exceed a value of 16, which would be invalid hex. Is this correct?
No, it's because only versions 0 - 16 are specified. Other versions might behave entirely differently. (As an aside, if it were a comparison for the sake of clamping to the range of a single hex character the test would be >15 not >16).
answered yesterday
G. MaxwellG. Maxwell
3,4681630
Ah, I see now. Also, dec.data[0] is a byte's worth of data (two hex chars), which can hold 256 different states.
– kawthuldrok
49 mins ago
add a comment |
I'm assuming that the "dec.data[0] > 16" check is to make sure that the byte at index zero doesn't exceed a value of 16, which would be invalid hex. Is this correct?
No, it's because only versions 0 - 16 are specified. Other versions might behave entirely differently. (As an aside, if it were a comparison for the sake of clamping to the range of a single hex character the test would be >15 not >16).
answered yesterday
G. MaxwellG. Maxwell
3,4681630
I'm assuming that the "dec.data[0] > 16" check is to make sure that the byte at index zero doesn't exceed a value of 16, which would be invalid hex. Is this correct?
No, it's because only versions 0 - 16 are specified. Other versions might behave entirely differently. (As an aside, if it were a comparison for the sake of clamping to the range of a single hex character the test would be >15 not >16).
answered yesterday
G. MaxwellG. Maxwell
3,4681630
answered yesterday
G. MaxwellG. Maxwell
3,4681630
answered yesterday
G. MaxwellG. Maxwell
3,4681630
answered yesterday
G. MaxwellG. Maxwell
3,4681630
3,4681630
Ah, I see now. Also, dec.data[0] is a byte's worth of data (two hex chars), which can hold 256 different states.
– kawthuldrok
49 mins ago
add a comment |
Ah, I see now. Also, dec.data[0] is a byte's worth of data (two hex chars), which can hold 256 different states.
– kawthuldrok
49 mins ago
Ah, I see now. Also, dec.data[0] is a byte's worth of data (two hex chars), which can hold 256 different states.
– kawthuldrok
49 mins ago
Ah, I see now. Also, dec.data[0] is a byte's worth of data (two hex chars), which can hold 256 different states.
– kawthuldrok
49 mins ago
add a comment |
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