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Fix for SHA256 DS downgrade. And test of resistance.

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git-svn-id: file:///svn/unbound/trunk@1273 be551aaa-1e26-0410-a405-d3ace91eadb9
This commit is contained in:
Wouter Wijngaards 2008-09-30 10:42:02 +00:00
parent d4fadf55a8
commit 13a68aac89
6 changed files with 433 additions and 8 deletions
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4
doc/Changelog
View file

@ -1,3 +1,7 @@
30 September 2008: Wouter
- fixup SHA256 DS downgrade, no longer possible to downgrade to SHA1.
- tests for sha256 support and downgrade resistance.
29 September 2008: Wouter
- EDNS lameness detection, if EDNS packets are dropped this is
detected, eventually.

200
testdata/val_ds_sha2.rpl vendored Normal file
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@ -0,0 +1,200 @@
; config options
; The island of trust is at example.com
server:
trust-anchor: "example.com. 3600 IN DS 2854 3 1 46e4ffc6e9a4793b488954bd3f0cc6af0dfb201b"
val-override-date: "20070916134226"
stub-zone:
name: "."
stub-addr: 193.0.14.129 # K.ROOT-SERVERS.NET.
CONFIG_END
SCENARIO_BEGIN Test validator with SHA256 DS digest
; K.ROOT-SERVERS.NET.
RANGE_BEGIN 0 100
ADDRESS 193.0.14.129
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
SECTION QUESTION
. IN NS
SECTION ANSWER
. IN NS K.ROOT-SERVERS.NET.
SECTION ADDITIONAL
K.ROOT-SERVERS.NET. IN A 193.0.14.129
ENTRY_END
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
SECTION QUESTION
www.sub.example.com. IN A
SECTION AUTHORITY
com. IN NS a.gtld-servers.net.
SECTION ADDITIONAL
a.gtld-servers.net. IN A 192.5.6.30
ENTRY_END
RANGE_END
; a.gtld-servers.net.
RANGE_BEGIN 0 100
ADDRESS 192.5.6.30
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
SECTION QUESTION
com. IN NS
SECTION ANSWER
com. IN NS a.gtld-servers.net.
SECTION ADDITIONAL
a.gtld-servers.net. IN A 192.5.6.30
ENTRY_END
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
SECTION QUESTION
www.sub.example.com. IN A
SECTION AUTHORITY
example.com. IN NS ns.example.com.
SECTION ADDITIONAL
ns.example.com. IN A 1.2.3.4
ENTRY_END
RANGE_END
; ns.example.com.
RANGE_BEGIN 0 100
ADDRESS 1.2.3.4
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
SECTION QUESTION
example.com. IN NS
SECTION ANSWER
example.com. IN NS ns.example.com.
example.com. 3600 IN RRSIG NS 3 2 3600 20070926134150 20070829134150 2854 example.com. MC0CFQCN+qHdJxoI/2tNKwsb08pra/G7aAIUAWA5sDdJTbrXA1/3OaesGBAO3sI= ;{id = 2854}
SECTION ADDITIONAL
ns.example.com. IN A 1.2.3.4
ns.example.com. 3600 IN RRSIG A 3 3 3600 20070926135752 20070829135752 2854 example.com. MC0CFQCMSWxVehgOQLoYclB9PIAbNP229AIUeH0vNNGJhjnZiqgIOKvs1EhzqAo= ;{id = 2854}
ENTRY_END
; response to DNSKEY priming query
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
SECTION QUESTION
example.com. IN DNSKEY
SECTION ANSWER
example.com. 3600 IN DNSKEY 256 3 3 ALXLUsWqUrY3JYER3T4TBJII s70j+sDS/UT2QRp61SE7S3E EXopNXoFE73JLRmvpi/UrOO/Vz4Se 6wXv/CYCKjGw06U4WRgR YXcpEhJROyNapmdIKSx hOzfLVE1gqA0PweZR8d tY3aNQSRn3sPpwJr6Mi /PqQKAMMrZ9ckJpf1+b QMOOvxgzz2U1GS18b3y ZKcgTMEaJzd/GZYzi/B N2DzQ0MsrSwYXfsNLFO Bbs8PJMW4LYIxeeOe6rUgkWOF 7CC9Dh/dduQ1QrsJhmZAEFfd6ByYV+ ;{id = 2854 (zsk), size = 1688b}
example.com. 3600 IN RRSIG DNSKEY DSA 2 3600 20070926134150 20070829134150 2854 example.com. MCwCFBQRtlR4BEv9ohi+PGFjp+AHsJuHAhRCvz0shggvnvI88DFnBDCczHUcVA== ;{id = 2854}
SECTION AUTHORITY
example.com. IN NS ns.example.com.
example.com. 3600 IN RRSIG NS 3 2 3600 20070926134150 20070829134150 2854 example.com. MC0CFQCN+qHdJxoI/2tNKwsb08pra/G7aAIUAWA5sDdJTbrXA1/3OaesGBAO3sI= ;{id = 2854}
SECTION ADDITIONAL
ns.example.com. IN A 1.2.3.4
ns.example.com. 3600 IN RRSIG A 3 3 3600 20070926135752 20070829135752 2854 example.com. MC0CFQCMSWxVehgOQLoYclB9PIAbNP229AIUeH0vNNGJhjnZiqgIOKvs1EhzqAo= ;{id = 2854}
ENTRY_END
; response for delegation to sub.example.com.
ENTRY_BEGIN
MATCH opcode subdomain
ADJUST copy_id copy_query
REPLY QR NOERROR
SECTION QUESTION
sub.example.com. IN A
SECTION ANSWER
SECTION AUTHORITY
sub.example.com. IN NS ns.sub.example.com.
; SHA256 DS for sub.example.com.
sub.example.com. 3600 IN DS 30899 5 2 51be8e847cc663f2775d0f2b6d15e41553c97ecb99b8dd667f18244e2f652033
sub.example.com. 3600 IN RRSIG DS 3 3 3600 20070926135752 20070829135752 2854 example.com. AJ6FL7yKjrpEEO8WMKlG7TVZoGjgFblJeu0rkJCmJxfdeh6ysUlWQWs= ;{id = 2854}
; SHA1 DS for sub.example.com.
;sub.example.com. 3600 IN DS 30899 RSASHA1 1 f7ed618f24d5e5202927e1d27bc2e84a141cb4b3
SECTION ADDITIONAL
ns.sub.example.com. IN A 1.2.3.6
ENTRY_END
RANGE_END
; ns.sub.example.com.
RANGE_BEGIN 0 100
ADDRESS 1.2.3.6
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
SECTION QUESTION
sub.example.com. IN NS
SECTION ANSWER
sub.example.com. IN NS ns.sub.example.com.
sub.example.com. 3600 IN RRSIG NS 5 3 3600 20070926134150 20070829134150 30899 sub.example.com. wcpHeBILHfo8C9uxMhcW03gcURZeUffiKdSTb50ZjzTHgMNhRyMfpcvSpXEd9548A9UTmWKeLZChfr5Z/glONw== ;{id = 30899}
SECTION ADDITIONAL
ns.sub.example.com. IN A 1.2.3.6
ns.sub.example.com. 3600 IN RRSIG A 5 4 3600 20070926134150 20070829134150 30899 sub.example.com. UF7shD/gt1FOp2UHgLTNbPzVykklSXFMEtJ1xD+Hholwf/PIzd7zoaIttIYibNa4fUXCqMg22H9P7MRhfmFe6g== ;{id = 30899}
ENTRY_END
; response to DNSKEY priming query
; sub.example.com. 3600 IN DS 30899 RSASHA1 1 f7ed618f24d5e5202927e1d27bc2e84a141cb4b3
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
SECTION QUESTION
sub.example.com. IN DNSKEY
SECTION ANSWER
sub.example.com. 3600 IN DNSKEY 256 3 5 AQPQ41chR9DEHt/aIzIFAqanbDlRflJoRs5yz1jFsoRIT7dWf0r+PeDuewdxkszNH6wnU4QL8pfKFRh5PIYVBLK3 ;{id = 30899 (zsk), size = 512b}
sub.example.com. 3600 IN RRSIG DNSKEY 5 3 3600 20070926134150 20070829134150 30899 sub.example.com. uNGp99iznjD7oOX02XnQbDnbg75UwBHRvZSKYUorTKvPUnCWMHKdRsQ+mf+Fx3GZ+Fz9BVjoCmQqpnfgXLEYqw== ;{id = 30899}
SECTION AUTHORITY
sub.example.com. IN NS ns.sub.example.com.
sub.example.com. 3600 IN RRSIG NS 5 3 3600 20070926134150 20070829134150 30899 sub.example.com. wcpHeBILHfo8C9uxMhcW03gcURZeUffiKdSTb50ZjzTHgMNhRyMfpcvSpXEd9548A9UTmWKeLZChfr5Z/glONw== ;{id = 30899}
SECTION ADDITIONAL
ns.sub.example.com. IN A 1.2.3.6
ns.sub.example.com. 3600 IN RRSIG A 5 4 3600 20070926134150 20070829134150 30899 sub.example.com. UF7shD/gt1FOp2UHgLTNbPzVykklSXFMEtJ1xD+Hholwf/PIzd7zoaIttIYibNa4fUXCqMg22H9P7MRhfmFe6g== ;{id = 30899}
ENTRY_END
; response to query of interest
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
SECTION QUESTION
www.sub.example.com. IN A
SECTION ANSWER
www.sub.example.com. IN A 11.11.11.11
www.sub.example.com. 3600 IN RRSIG A 5 4 3600 20070926134150 20070829134150 30899 sub.example.com. 0DqqRfRtm7VSEQ4mmBbzrKRqQAay3JAE8DPDGmjtokrrjN9F1G/HxozDV7bjdIh2EChlQea8FPwf/GepJMUVxg== ;{id = 30899}
SECTION AUTHORITY
SECTION ADDITIONAL
ENTRY_END
RANGE_END
STEP 1 QUERY
ENTRY_BEGIN
REPLY RD DO
SECTION QUESTION
www.sub.example.com. IN A
ENTRY_END
; recursion happens here.
STEP 10 CHECK_ANSWER
ENTRY_BEGIN
MATCH all
REPLY QR RD RA AD NOERROR
SECTION QUESTION
www.sub.example.com. IN A
SECTION ANSWER
www.sub.example.com. 3600 IN A 11.11.11.11
www.sub.example.com. 3600 IN RRSIG A 5 4 3600 20070926134150 20070829134150 30899 sub.example.com. 0DqqRfRtm7VSEQ4mmBbzrKRqQAay3JAE8DPDGmjtokrrjN9F1G/HxozDV7bjdIh2EChlQea8FPwf/GepJMUVxg== ;{id = 30899}
SECTION AUTHORITY
SECTION ADDITIONAL
ENTRY_END
SCENARIO_END

206
testdata/val_ds_sha2_downgrade.rpl vendored Normal file
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@ -0,0 +1,206 @@
; config options
; The island of trust is at example.com
server:
trust-anchor: "example.com. 3600 IN DS 2854 3 1 46e4ffc6e9a4793b488954bd3f0cc6af0dfb201b"
val-override-date: "20070916134226"
stub-zone:
name: "."
stub-addr: 193.0.14.129 # K.ROOT-SERVERS.NET.
CONFIG_END
SCENARIO_BEGIN Test validator with SHA256 DS downgrade to SHA1
; K.ROOT-SERVERS.NET.
RANGE_BEGIN 0 100
ADDRESS 193.0.14.129
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
SECTION QUESTION
. IN NS
SECTION ANSWER
. IN NS K.ROOT-SERVERS.NET.
SECTION ADDITIONAL
K.ROOT-SERVERS.NET. IN A 193.0.14.129
ENTRY_END
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
SECTION QUESTION
www.sub.example.com. IN A
SECTION AUTHORITY
com. IN NS a.gtld-servers.net.
SECTION ADDITIONAL
a.gtld-servers.net. IN A 192.5.6.30
ENTRY_END
RANGE_END
; a.gtld-servers.net.
RANGE_BEGIN 0 100
ADDRESS 192.5.6.30
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
SECTION QUESTION
com. IN NS
SECTION ANSWER
com. IN NS a.gtld-servers.net.
SECTION ADDITIONAL
a.gtld-servers.net. IN A 192.5.6.30
ENTRY_END
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
SECTION QUESTION
www.sub.example.com. IN A
SECTION AUTHORITY
example.com. IN NS ns.example.com.
SECTION ADDITIONAL
ns.example.com. IN A 1.2.3.4
ENTRY_END
RANGE_END
; ns.example.com.
RANGE_BEGIN 0 100
ADDRESS 1.2.3.4
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
SECTION QUESTION
example.com. IN NS
SECTION ANSWER
example.com. IN NS ns.example.com.
example.com. 3600 IN RRSIG NS 3 2 3600 20070926134150 20070829134150 2854 example.com. MC0CFQCN+qHdJxoI/2tNKwsb08pra/G7aAIUAWA5sDdJTbrXA1/3OaesGBAO3sI= ;{id = 2854}
SECTION ADDITIONAL
ns.example.com. IN A 1.2.3.4
ns.example.com. 3600 IN RRSIG A 3 3 3600 20070926135752 20070829135752 2854 example.com. MC0CFQCMSWxVehgOQLoYclB9PIAbNP229AIUeH0vNNGJhjnZiqgIOKvs1EhzqAo= ;{id = 2854}
ENTRY_END
; response to DNSKEY priming query
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
SECTION QUESTION
example.com. IN DNSKEY
SECTION ANSWER
example.com. 3600 IN DNSKEY 256 3 3 ALXLUsWqUrY3JYER3T4TBJII s70j+sDS/UT2QRp61SE7S3E EXopNXoFE73JLRmvpi/UrOO/Vz4Se 6wXv/CYCKjGw06U4WRgR YXcpEhJROyNapmdIKSx hOzfLVE1gqA0PweZR8d tY3aNQSRn3sPpwJr6Mi /PqQKAMMrZ9ckJpf1+b QMOOvxgzz2U1GS18b3y ZKcgTMEaJzd/GZYzi/B N2DzQ0MsrSwYXfsNLFO Bbs8PJMW4LYIxeeOe6rUgkWOF 7CC9Dh/dduQ1QrsJhmZAEFfd6ByYV+ ;{id = 2854 (zsk), size = 1688b}
example.com. 3600 IN RRSIG DNSKEY DSA 2 3600 20070926134150 20070829134150 2854 example.com. MCwCFBQRtlR4BEv9ohi+PGFjp+AHsJuHAhRCvz0shggvnvI88DFnBDCczHUcVA== ;{id = 2854}
SECTION AUTHORITY
example.com. IN NS ns.example.com.
example.com. 3600 IN RRSIG NS 3 2 3600 20070926134150 20070829134150 2854 example.com. MC0CFQCN+qHdJxoI/2tNKwsb08pra/G7aAIUAWA5sDdJTbrXA1/3OaesGBAO3sI= ;{id = 2854}
SECTION ADDITIONAL
ns.example.com. IN A 1.2.3.4
ns.example.com. 3600 IN RRSIG A 3 3 3600 20070926135752 20070829135752 2854 example.com. MC0CFQCMSWxVehgOQLoYclB9PIAbNP229AIUeH0vNNGJhjnZiqgIOKvs1EhzqAo= ;{id = 2854}
ENTRY_END
; response for delegation to sub.example.com.
ENTRY_BEGIN
MATCH opcode subdomain
ADJUST copy_id copy_query
REPLY QR NOERROR
SECTION QUESTION
sub.example.com. IN A
SECTION ANSWER
SECTION AUTHORITY
sub.example.com. IN NS ns.sub.example.com.
; Downgrade attack: false SHA2, correct SHA1
; SHA256 DS for sub.example.com.
;sub.example.com. 3600 IN DS 30899 5 2 51be8e847cc663f2775d0f2b6d15e41553c97ecb99b8dd667f18244e2f652033
; BAD SHA256 DS
sub.example.com. 3600 IN DS 30899 5 2 51be8e847cc663f2775d0f2b6d15e41553c97ecb99b8dd667f18244e2f652000
; SHA1 DS for sub.example.com.
sub.example.com. 3600 IN DS 30899 RSASHA1 1 f7ed618f24d5e5202927e1d27bc2e84a141cb4b3
sub.example.com. 3600 IN RRSIG DS 3 3 3600 20070926135752 20070829135752 2854 example.com. ACqqpk1ow07XJvN1orEpiWOeqMLdDKQtTgWB8Mp6CF/9VTfHuWWmsu8= ;{id = 2854}
SECTION ADDITIONAL
ns.sub.example.com. IN A 1.2.3.6
ENTRY_END
RANGE_END
; ns.sub.example.com.
RANGE_BEGIN 0 100
ADDRESS 1.2.3.6
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
SECTION QUESTION
sub.example.com. IN NS
SECTION ANSWER
sub.example.com. IN NS ns.sub.example.com.
sub.example.com. 3600 IN RRSIG NS 5 3 3600 20070926134150 20070829134150 30899 sub.example.com. wcpHeBILHfo8C9uxMhcW03gcURZeUffiKdSTb50ZjzTHgMNhRyMfpcvSpXEd9548A9UTmWKeLZChfr5Z/glONw== ;{id = 30899}
SECTION ADDITIONAL
ns.sub.example.com. IN A 1.2.3.6
ns.sub.example.com. 3600 IN RRSIG A 5 4 3600 20070926134150 20070829134150 30899 sub.example.com. UF7shD/gt1FOp2UHgLTNbPzVykklSXFMEtJ1xD+Hholwf/PIzd7zoaIttIYibNa4fUXCqMg22H9P7MRhfmFe6g== ;{id = 30899}
ENTRY_END
; response to DNSKEY priming query
; sub.example.com. 3600 IN DS 30899 RSASHA1 1 f7ed618f24d5e5202927e1d27bc2e84a141cb4b3
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
SECTION QUESTION
sub.example.com. IN DNSKEY
SECTION ANSWER
sub.example.com. 3600 IN DNSKEY 256 3 5 AQPQ41chR9DEHt/aIzIFAqanbDlRflJoRs5yz1jFsoRIT7dWf0r+PeDuewdxkszNH6wnU4QL8pfKFRh5PIYVBLK3 ;{id = 30899 (zsk), size = 512b}
sub.example.com. 3600 IN RRSIG DNSKEY 5 3 3600 20070926134150 20070829134150 30899 sub.example.com. uNGp99iznjD7oOX02XnQbDnbg75UwBHRvZSKYUorTKvPUnCWMHKdRsQ+mf+Fx3GZ+Fz9BVjoCmQqpnfgXLEYqw== ;{id = 30899}
SECTION AUTHORITY
sub.example.com. IN NS ns.sub.example.com.
sub.example.com. 3600 IN RRSIG NS 5 3 3600 20070926134150 20070829134150 30899 sub.example.com. wcpHeBILHfo8C9uxMhcW03gcURZeUffiKdSTb50ZjzTHgMNhRyMfpcvSpXEd9548A9UTmWKeLZChfr5Z/glONw== ;{id = 30899}
SECTION ADDITIONAL
ns.sub.example.com. IN A 1.2.3.6
ns.sub.example.com. 3600 IN RRSIG A 5 4 3600 20070926134150 20070829134150 30899 sub.example.com. UF7shD/gt1FOp2UHgLTNbPzVykklSXFMEtJ1xD+Hholwf/PIzd7zoaIttIYibNa4fUXCqMg22H9P7MRhfmFe6g== ;{id = 30899}
ENTRY_END
; response to query of interest
ENTRY_BEGIN
MATCH opcode qtype qname
ADJUST copy_id
REPLY QR NOERROR
SECTION QUESTION
www.sub.example.com. IN A
SECTION ANSWER
www.sub.example.com. IN A 11.11.11.11
www.sub.example.com. 3600 IN RRSIG A 5 4 3600 20070926134150 20070829134150 30899 sub.example.com. 0DqqRfRtm7VSEQ4mmBbzrKRqQAay3JAE8DPDGmjtokrrjN9F1G/HxozDV7bjdIh2EChlQea8FPwf/GepJMUVxg== ;{id = 30899}
SECTION AUTHORITY
SECTION ADDITIONAL
ENTRY_END
RANGE_END
STEP 1 QUERY
ENTRY_BEGIN
REPLY RD DO
SECTION QUESTION
www.sub.example.com. IN A
ENTRY_END
; recursion happens here.
; must servfail, BOGUS
STEP 10 CHECK_ANSWER
ENTRY_BEGIN
MATCH all
REPLY QR RD RA SERVFAIL
SECTION QUESTION
www.sub.example.com. IN A
SECTION ANSWER
;www.sub.example.com. 3600 IN A 11.11.11.11
;www.sub.example.com. 3600 IN RRSIG A 5 4 3600 20070926134150 20070829134150 30899 sub.example.com. 0DqqRfRtm7VSEQ4mmBbzrKRqQAay3JAE8DPDGmjtokrrjN9F1G/HxozDV7bjdIh2EChlQea8FPwf/GepJMUVxg== ;{id = 30899}
SECTION AUTHORITY
SECTION ADDITIONAL
ENTRY_END
SCENARIO_END

8
validator/val_sigcrypt.c
View file

@ -189,13 +189,7 @@ ds_get_key_algo(struct ub_packed_rrset_key* k, size_t idx)
return (int)rdata[2+2];
}
/**
* Get DS RR digest algorithm
* @param k: DS rrset.
* @param idx: which DS.
* @return algorithm or 0 if DS too short.
*/
static int
int
ds_get_digest_algo(struct ub_packed_rrset_key* k, size_t idx)
{
uint8_t* rdata;

8
validator/val_sigcrypt.h
View file

@ -99,6 +99,14 @@ int dnskey_algo_is_supported(struct ub_packed_rrset_key* dnskey_rrset,
int ds_digest_algo_is_supported(struct ub_packed_rrset_key* ds_rrset,
size_t ds_idx);
/*
* Get DS RR digest algorithm
* @param ds_rrset: DS rrset.
* @param ds_idx: which DS.
* @return algorithm or 0 if DS too short.
*/
int ds_get_digest_algo(struct ub_packed_rrset_key* ds_rrset, size_t ds_idx);
/**
* See if DS key algorithm is supported
* @param ds_rrset: DS rrset

15
validator/val_utils.c
View file

@ -421,6 +421,7 @@ val_verify_new_DNSKEYs(struct regional* region, struct module_env* env,
/* as long as this is false, we can consider this DS rrset to be
* equivalent to no DS rrset. */
int has_useful_ds = 0;
int d, digest_algo = 0; /* DS digest algo 0 is not used. */
size_t i, num;
enum sec_status sec;
@ -435,12 +436,24 @@ val_verify_new_DNSKEYs(struct regional* region, struct module_env* env,
}
num = rrset_get_count(ds_rrset);
/* find favority algo, for now, highest number supported */
for(i=0; i<num; i++) {
/* Check to see if we can understand this DS. */
if(!ds_digest_algo_is_supported(ds_rrset, i) ||
!ds_key_algo_is_supported(ds_rrset, i)) {
continue;
}
d = ds_get_digest_algo(ds_rrset, i);
if(d > digest_algo)
digest_algo = d;
}
for(i=0; i<num; i++) {
/* Check to see if we can understand this DS.
* And check it is the strongest digest */
if(!ds_digest_algo_is_supported(ds_rrset, i) ||
!ds_key_algo_is_supported(ds_rrset, i) ||
ds_get_digest_algo(ds_rrset, i) != digest_algo) {
continue;
}
/* Once we see a single DS with a known digestID and
* algorithm, we cannot return INSECURE (with a